This problem (like many others) tests logical meaning. Note the use of the word "other" in choices "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.", and compare that to the usage in "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because of some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any European country."/"Because it has some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than any European country does.". Can the UK have more invasive species than any European country, when it is a European country itself? Logically, no - it can have the most of any country in Europe, but not more than any country. The best it can do is "tie" itself. So this sentence requires the use of "other" to be logically correct.

Then notice the major difference between "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." and "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country.". The UK has some of the busiest (air)ports, but it is not itself the busiest airports and ports. So "As some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." is illogical, meaning that "With some of the busiest airports and ports in Europe, the United Kingdom has far more invasive species of certain types than does any other European country." must be the correct answer.

This problem provides two very clear decision points for you to get started:

1) "they" vs. "it" as the first word of the sentence

2) "that of" vs. "those of" vs. (no possessive) in relation to "the Medieval period"

The key to both of these is recognizing the subject of the sentence which is "global temperatures." Since temperatures is plural, the pronoun that corresponds to them must be "they" and you can eliminate choices "it has only recently eclipsed the Medieval period, during which, scientists theorize, a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a".

Then notice that the comparison is between current global temperatures and the temperatures during the Medieval period; you cannot logically compare "temperatures" with the timeframe, so you need to have "those of" (which "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a" have but "they have only recently eclipsed the Medieval period, during which scientists theorize that a" does not) to properly draw the comparison.

Between "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a", notice that the only difference is commas around "during which." Why is that important? Here you're dealing with a tense/timeline decision. Since "theorize" is present-tense but the Medieval period is clearly in the past (even if you're not a historian, the fixed past tense "sent" outside the underline tells you that those volcanoes were in the past), you cannot have "scientists theorize" as part of the phrase "during which." The scientists currently theorize that volcanoes caused the global warming, so you need to separate that subject-verb from the modifier "during (the Medieval period)." This means that answer choice "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a" is correct.

In this sentence correction problem, it is very easy to access the decision points because there is only one word underlined! So the difference between those five choices to start the sentence obviously matters and you need to figure out why.

To do this you must look at the entire sentence - a classic example of the “Whole Sentence Matters” device used by testmakers. The primary issue is which of these modifiers creates logical meaning with the rest of the sentence. Clearly, the phrase must modify “rainforests”- and do rainforests “have” or “possess” a portion of the earth’s surface? Or do they just represent it? They simply are that portion of the earth’s surface, so only “as” "being" and “although accounting for” could be correct choices. Answer choices "With" and "Despite having" illogically suggest that rainforests have or are with 7% of the world's surface areas.

For the choice between "As", "Being" and "Although accounting for", the decision comes down to the meaning of the sentence. The rest of the sentence goes on to talk about what a large impact the rainforest have on the planet, but the introductory phrase talks about how rainforests are (only) 7% of the earth’s surface. Answer choices "As" and "Being" illogically suggest that the reason they have such a large impact is because they are such a small percentage of the earth's surface area! With that in mind, you see that the sentence requires a transition to set up a logical meaning – although rainforests represent a small area, they have a huge impact. Therefore, the phrase “although accounting for” is necessary, and the correct answer is "Although accounting for".

The only decision points in this problem are the choice between "and" and "or" at the end of the series and the choice in how the series are constructed. Each one of these separate things - genetic engineering, ionizing radiation, and sewage sludge - is something that if true would prevent anything from being labeled organic. You do not need all three to be disqualified from being labeled organic so the word "and" is incorrect - it must be "or". Similarly the words "as well as" in "genetic engineering or ionizing radiation, as well as the use of sewage sludge," create the same problem so you can eliminate "genetic engineering or ionizing radiation, and with sewage sludge,", "genetic engineering or ionizing radiation, as well as the use of sewage sludge,", and "genetic engineering, ionizing radiation, and sewage sludge" for this reason. "genetic engineering or ionizing radiation, or the use of sewage sludge," is a fairly easy-to-recognize error of parallelism in the series so correct answer is "genetic engineering, ionizing radiation, or sewage sludge".

"supermoon, which is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, and which can make the moon appear" contains a sentence construction error: the subject "supermoon" never gets a verb, so we are left with a fragment. "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" suggests either that "a supermoon" can make the moon appear larger or that "the moon" can make the moon appear larger, but neither of these construals is acceptable, since a supermoon is the moon and one would never say that "the moon makes the moon appear larger." "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears" correctly suggests either that "a supermoon" appears much larger than the moon typically does or that "the moon" appears much larger than the moon typically does. In "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, a position which causes itself to appear", the phrase "causes itself" does not work logically, since the position does not make itself appear larger. "supermoon, which is the full or new moon that occurs when the moon is at or near its closest approach to the Earth, causes the moon to appear" suggests that the "supermoon" causes the moon to appear larger, but that claim is illogical, since the "supermoon" is the moon. Note: "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" and "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears are both characterized by the same flexible/fuzzy subject-verb relationships. In "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear", either "a supermoon" or "the moon" (first instance) could be legitimately posited as the subject of "can make"; in "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears", either "a supermoon" or "the moon" (first instance) could be legitimately posited as the subject of "appears." What's important is that whichever construct one favors, the reasoning above holds: "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and can make the moon appear" doesn't work and "supermoon is the full or new moon that occurs when the moon is at or near its closest approach to the Earth and appears" does.

In these “Weaken the Plan” questions, your job is to find a reason that the plan will not work. And "The train line taken by most Plymouth Soccer Club spectators to the stadium arrives every four hours starting at 11:30am." supplies one – if most people cannot arrive before 11:30am, they won’t be able to respond to the new promotion of events before a noon game. Choice "The neighboring Canton Soccer Club has found that the best way to incent spectators to arrive early is to discount all concessions up to an hour before kickoff."is incorrect in that the potential existence of a better plan doesn’t necessarily mean that this plan will not work. Similarly choice "The children’s exhibitions will likely tear up the turf before the premier match begins, resulting in a lower-quality playing surface for the main event." is out of scope – the field quality is irrelevant as to whether the plan will reach its objective of reducing congestion near game time. Choices "Some fans of the Plymouth Soccer Club must travel for several hours to attend matches at the stadium." and "Because of its original design, the stadium used by Plymouth Soccer Club has fewer entryways than any other stadium in the surrounding area.", similarly, do not hinder the plan’s chance of reaching its objective.

In this Plan/Strategy question, the goal is to reduce a nation's energy consumption, and the plan is to require tenants to be the payers of utility bills (as opposed to the owners of those properties). Remember: with Plan/Strategy questions, two concepts are crucial:

1) Pay close attention to the specific goal, which plays the same role as the conclusion in a classic Strengthen/Weaken question. Trap answers are often related to the general topic but do not affect the specific goal.

2) A better plan does not weaken the provided plan! Your job is only to assess whether this plan will achieve this objective, not whether it's the best plan, the most efficient plan, etc.

Note that each of "Most of the country's energy consumption comes from commercial real estate, not residential real estate." and "Other nations have had success reducing energy consumption by offering rental subsidies for tenants whose energy usage falls below certain thresholds." suggests a "better plan" - "Most of the country's energy consumption comes from commercial real estate, not residential real estate." suggests that this plan wouldn't be as effective as one that tackled energy usage in commercial real estate and E suggests that rental subsidies could be a better program. But neither directly weakens this plan: as long as less energy is used under this plan, the plan has achieved its goal of reducing energy usage. So "Most of the country's energy consumption comes from commercial real estate, not residential real estate." and "Other nations have had success reducing energy consumption by offering rental subsidies for tenants whose energy usage falls below certain thresholds." may be tempting, but they are incorrect.

Choice "When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions." is correct: if giving the tenants an incentive to use less energy also remove the incentive for the landowners to pursue energy-saving policies, that suggests that this plan may not work at all: it may not result in any energy reduction.

Choices "Most rental properties are rented by younger people, and people tend to be more conscious about environmental issues like energy consumption when they are younger." and "Energy bills are calculated not only by the amount of energy used, but also by the times of day during which energy is used." are too far from the scope of the current plan and its goal, and are also incorrect. "When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions." is the correct choice.

In any Plan/Strategy question, it is important to determine exactly what the goal of the plan is. Here the goal is to "substantially reduce marijuana use," which you should see is different from related goals (perhaps to reduce marijuana sales or to eliminate marijuana use). Precision in wording and understanding the exact goal are keys to these questions.

You can anticipate reasons that raising the sales tax and therefore the cost of marijuana might not result in a significant decrease in marijuana use. Focusing on use - and not sales - provides a great entry point: what if people find a way to get marijuana without having to buy it? Choice "The state law that legalized marijuana also allows residents to grow a small amount of marijuana for personal use.​" suggests that they might be able to simply grow it on their own and avoid both the price and the tax.

What if they can buy it somewhere else and avoid the tax? That leads to answer choices:

"Despite the legalization of marijuana, there remains a non-trivial black market for the illegal sale of marijuana in Kerry County.": If people can buy it on the black market and avoid paying the sales tax, then they can still use it without being affected by the tax.

"Kerry County is among the smallest counties in the state, with no location that is more than a 20-minute drive from a neighboring county.": If people can buy it nearby in a county that doesn't have the tax, then they'll avoid the tax.

What if the tax just isn't that big of a deterrent? Choice "Marijuana use has been most popular among young professionals, a demographic that tends to have a large amount of disposable income." suggests that the largest group of users may must not care about paying more to use marijuana.

That leaves choice "Kerry County already levies similar "sin tax" sales taxes on other recreational drugs such as alcohol and tobacco.", which you should see does not directly address marijuana at all. Even if similar taxes for similar goods are already on the books, that still means that the net cost of marijuana will markedly increase under the sales tax. If that is, indeed, a deterrent then the taxes on similar goods won't matter. "Kerry County already levies similar "sin tax" sales taxes on other recreational drugs such as alcohol and tobacco." does not attack the problem head on, and is therefore the only answer choice that does not give reason to believe that the plan will not work.

The strategy outlined in this Weaken problem makes a classic error of correlation vs. causation, assuming that "bringing lunch to work" is a cause of "takes fewer sick days." In actuality, it could be that bringing lunch is an effect of a totally different cause, as choice "Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch." correctly points out. With choice "Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch.", the cause of both "brings lunch to work" and "takes fewer sick days" is that generally-healthier people do both - they bring their lunch to work and they take fewer sick days. Forcing someone else - someone less healthy - to bring his or her lunch wouldn't change the other unhealthy habits that lead to extra sick days, so the plan would not work.

While choice "Boltech's cafeteria is known for serving a diverse array of healthy lunch options." seems like it should weaken the plan (taking away the healthy options at the cafeteria), keep in mind that we already have the evidence that those who bring their lunch take fewer sick days than those who eat at the cafeteria, so those healthy cafeteria options have already been called into question as a driver of fewer sick days.

Choice "Because of Boltech's location, employees who choose to visit a nearby restaurant for lunch will seldom be able to return within an hour." could very well be correct if the goal were to minimize "time away from one's desk" or something similar, but the goal is specifically called out as "fewer sick days." Being away for a longer period for lunch may well be a problem worth considering, but in the context of this particular goal it is irrelevant.

Choice "Employees have expressed concern about the cost of dining at nearby restaurants compared with the affordability of the Boltech cafeteria." is similar: it shows a reason why the plan might not be a great plan overall (it could hurt employee morale) but the goal is specifically drawn at "fewer sick days" so that morale is irrelevant to the specific aims in the problem. For similar reasons, choice "Many Boltech employees chose to work for the company in large part because of its generous benefits, such as an on-site cafeteria and fitness center." is also incorrect - while morale may be hurt and people might feel misled (or future recruitment efforts may fall short), the only objective specifically addressed in the problem is "reduce the number of sick days" so choice "Many Boltech employees chose to work for the company in large part because of its generous benefits, such as an on-site cafeteria and fitness center." is not relevant.

In this Weaken the Plan question, the goal is to solve problems of high unemployment and a lack of qualified candidates for certain jobs. The plan, then, is to offer a free training program to unemployed citizens to prepare them for those jobs. But if "Successful graduates of technical training programs nearly always have scientific job experience prior to enrolling in such programs." were true - if the program required related job experience beforehand to be successful - then that plan is not likely to work on its own. Note that choices "Many universities and technical colleges offer nine- and twelve-month programs to train students in the same fields." and "The proposed program is significantly more expensive than several alternatives proposed by members of the legislative body." both commit the "cardinal sin" of Weaken the Plan questions - they propose better plans, but don't weaken this plan. Choice "Laboratory and medical technician jobs are not the only jobs for which companies are struggling to find qualified employees." is also incorrect; the goal isn't to "eliminate unemployment" but rather just to lessen it, and so "Laboratory and medical technician jobs are not the only jobs for which companies are struggling to find qualified employees." does not weaken the plan. And choice "Similar programs in neighboring countries have had mixed results." neither strengthens nor weaken the plan - it shows that there is a possibility that the plan could work and that it could not based on prior evidence, and doesn't give any reason to believe that this plan will fall in the "not" column.