The correct answer is "reduce." "Reduce" means make smaller or lessen. The other words can all make sense grammatically in the sentence, but reduce makes the most sense given that the sentence begins with the phrase "To help the environment."

The context of the sentence tells us that the doctors worked tirelessly to bring the man back to consciousness, and this is the meaning of the word “revive.” In English, the root "viv" means life or living as in “revive,” “survive,” “vitality,” and “vitamins." None of the other answer choices make sense in the blank: when used as a verb, “convict” means successfully bring criminal charges against in court, and when used as a noun, a "convict" is a criminal; “expose” means reveal; to “conjecture” is to guess; and “supplant” means replace.

When you put something off to be continued later, you “postpone” it. So, because the tennis match was stopped because of the rain and planned to be finished the next day, the correct answer is “postponed.” The word “outlawed” means banned or not allowed, and “restored” means put back into original condition.

The context of the sentence tells you that the secretary can rotate his chair so that he can focus on the whole office. You are therefore looking for an answer choice that has a similar meaning to "rotate." The correct answer is therefore "swivel." To provide further help, "demolish" means destroy, tear down; "replenish" means refuel, restock; "dispose" means throw away; "undulate" means wave.

In this sentence the teacher asks the student to go home and change his work. Based on the structure of this sentence you know that the blank word must be a verb that means "change." The correct answer is therefore "alter." To provide further help, "postpone" means delay until later; "sprint" means run fast; "conceal" means hide; "prefer" means like more than another thing. 

The children who are the subject of this sentence are doing something happily by the side of the river in summertime. From context we can reasonably infer that the children are playing, so you need to find an answer choice that means something similar to "play." The correct answer is "frolic" which means to play, to have fun. To provide further help, "labor" means work; "consume" means eat; "retire" means stop working, stop doing something; "panic" means to freak out. 

To solve this problem you need to determine which of these answer choices refers to the action of bringing a product into a country from abroad. The correct answer is therefore "imported." The opposite of "import" is "export" which means to send products to another country. So, bananas are "exported" from Costa Rica and "imported" into the United States. Additionally, "detached," when used as a verb, means separated, broken up, split; "spurred" means encouraged, helped on; "irked" means annoyed, frustrated, angered; "shrouded" means concealed or hidden. 

To solve this problem you have to determine which of these answer choices means to remember specific things from the past. The correct answer is therefore "recollect." Synonyms of "recollect" include recall, remember, think back to. Additionally, subtract" means take away from; "forsake" means abandon, desert, forget; "strive" means work hard for; "navigate" means to plan and guide the movement of a vehicle.

Based on the context of this sentence you are looking for an answer choice that means to remove, to take from a place. The correct answer is therefore "extract." Synonyms of "extract" include withdraw, remove, take out, take from. Additionally, "revert" means to back to a previous state; "petrify" means to shock or stun; "merge" means to mix, to blend; "contradict" means argue against.

To solve this problem you need to determine which of these words means something like to kill or get rid of something completely. The correct answer is therefore "exterminate." Synonyms of "exterminate" include kill, get rid of. Additionally, "taunt" means mock and tease; "astound" means amaze, stun and shock; "transport" means move something from one place to another; "compress" means shrink to a smaller size.