Adapted from "Wasps" by Thomas G. Belt in A Book of Natural History (1902, ed. David Starr Jordan)

One day I saw a small black and yellow banded wasp hunting for spiders; it approached a web where a spider was stationed in the center, made a dart towards it—apparently a feint to frighten the spider clear of its web; at any rate it had that effect, for it fell to the ground, and was immediately seized by the wasp, who stung it, then ran quickly backwards, dragging the spider after it, up a branch reaching to the ground until it got high enough, when it flew heavily off with it. It was so small, and the spider so cumbersome, that it probably could not have raised it from the ground by flight.

All over the world there are wasps that store their nests with the bodies of spiders for their young to feed on. In Australia, I often witnessed a wasp engaging with a large flat spider that is found on the bark of trees. It would fall to the ground, and lie on its back, so as to be able to grapple with its opponent; but the wasp was always the victor in the encounters I saw, although it was not always allowed to carry off its prey in peace. One day, sitting on the sandbanks on the coast of Hobson’s Bay, I saw one dragging along a large spider. Three or four inches above it hovered two minute flies, keeping a little behind, and advancing with it. The wasp seemed much disturbed by the presence of the tiny flies, and twice left its prey to fly up towards them, but they darted away with it. As soon as the wasp returned to the spider, there they were hovering over and following it again. At last, unable to drive away its small provocateurs, the wasp reached its burrow and took down the spider, and the two flies stationed themselves one on each side of the entrance, and would, doubtless, when the wasp went away to seek another victim, descend and lay their own eggs in the nest.

The underlined word “provocateurs” most nearly means __________.

Adapted from "Wasps" by Thomas G. Belt in A Book of Natural History (1902, ed. David Starr Jordan)

One day I saw a small black and yellow banded wasp hunting for spiders; it approached a web where a spider was stationed in the center, made a dart towards it—apparently a feint to frighten the spider clear of its web; at any rate it had that effect, for it fell to the ground, and was immediately seized by the wasp, who stung it, then ran quickly backwards, dragging the spider after it, up a branch reaching to the ground until it got high enough, when it flew heavily off with it. It was so small, and the spider so cumbersome, that it probably could not have raised it from the ground by flight.

All over the world there are wasps that store their nests with the bodies of spiders for their young to feed on. In Australia, I often witnessed a wasp engaging with a large flat spider that is found on the bark of trees. It would fall to the ground, and lie on its back, so as to be able to grapple with its opponent; but the wasp was always the victor in the encounters I saw, although it was not always allowed to carry off its prey in peace. One day, sitting on the sandbanks on the coast of Hobson’s Bay, I saw one dragging along a large spider. Three or four inches above it hovered two minute flies, keeping a little behind, and advancing with it. The wasp seemed much disturbed by the presence of the tiny flies, and twice left its prey to fly up towards them, but they darted away with it. As soon as the wasp returned to the spider, there they were hovering over and following it again. At last, unable to drive away its small provocateurs, the wasp reached its burrow and took down the spider, and the two flies stationed themselves one on each side of the entrance, and would, doubtless, when the wasp went away to seek another victim, descend and lay their own eggs in the nest.

The underlined word “engaging” most nearly means __________.

Adapted from "Birds’ Nests" by John Burroughs in A Book of Natural History (1902, ed. David Starr Jordan)

The rarest of all nests is that of the eagle, because the eagle is the rarest of all birds. Indeed, so seldom is the eagle seen, that its presence always seems accidental. It appears as if merely pausing on the way, while bound for some distant unknown region. One September, while a youth, I saw the ring-tailed eagle, an immense bird, the sight of which filled me with awe. It lingered about the hills for two days. Some young cattle, a two year-old colt, and half a dozen sheep were at pasture on a high ridge that led up to the mountain, and in plain view of the house. On the second day, this dusky monarch was seen flying about above them. Presently he began to hover over them, after the manner of a hawk watching for mice. He then with extended legs let himself slowly down upon them, actually grappling the backs of the young cattle, and frightening the creatures so that they rushed about the field in great consternation; and finally, as he grew bolder and more frequent in his descents, the whole herd broke over the fence, and came tearing down to the house “like mad.” It did not seem to be an assault with intent to kill, but was, perhaps, a stratagem resorted to in order to separate the herd and expose the lambs, which hugged the cattle very closely. When he occasionally alighted upon the oaks that stood near, the branch could be seen to sway and bend beneath him. Finally, as a rifleman started out in pursuit of him, he launched into the air, set his wings, and sailed away southward. A few years afterward, in January, another eagle passed through the same locality, alighting in a field near some dead animal, but tarried briefly.

The underlined word “seldom” most nearly means __________.

Adapted from "Rain and Snow" by John Tyndall in Wonders of Earth, Sea, and Sky (1902, ed. by Edward Singleton Holden)

At the equator, and within certain limits north and south of it, the sun at certain periods of the year is directly overhead at noon. These limits are called the Tropics of Cancer and of Capricorn. Upon the belt comprised between these two circles, the sun's rays fall with their mightiest power, for here they shoot directly downwards and heat both earth and sea more than when they strike slantingly. When the vertical sunbeams strike the land, they heat it, and the air in contact with the hot soil becomes heated in turn. But when heated, the air expands, and when it expands, it becomes lighter. This lighter air rises through the heavier air overhead.

When the sunbeams fall upon the sea, the water is warmed, though not so much as the land. The warmed water expands, becomes thereby lighter, and therefore continues to float upon the top. This upper layer of water warms to some extent the air in contact with it, but it also sends up a quantity of aqueous vapor, which being far lighter than air helps the latter to rise. Thus both from the land and from the sea we have ascending currents established by the action of the sun.

The underlined word “ascending” most nearly means __________.

Adapted from "How the Soil is Made" by Charles Darwin in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

Worms have played a more important part in the history of the world than most persons would at first suppose. In almost all humid countries they are extraordinarily numerous, and for their size possess great muscular power. In many parts of England a weight of more than ten tons (10,516 kilograms) of dry earth annually passes through their bodies and is brought to the surface on each acre of land, so that the whole superficial bed of vegetable mould passes through their bodies in the course of every few years. From the collapsing of the old burrows, the mold is in constant though slow movement, and the particles composing it are thus rubbed together. Thus the particles of earth, forming the superficial mold, are subjected to conditions eminently favorable for their decomposition and disintegration. This keeps the surface of the earth perfectly suited to the growth of an abundant array of fruits and vegetables.

Worms are poorly provided with sense-organs, for they cannot be said to see, although they can just distinguish between light and darkness; they are completely deaf, and have only a feeble power of smell; the sense of touch alone is well developed. They can, therefore, learn little about the outside world, and it is surprising that they should exhibit some skill in lining their burrows with their castings and with leaves, and in the case of some species in piling up their castings into tower-like constructions. But it is far more surprising that they should apparently exhibit some degree of intelligence instead of a mere blind, instinctive impulse, in their manner of plugging up the mouths of their burrows. They act in nearly the same manner as would a man, who had to close a cylindrical tube with different kinds of leaves, petioles, triangles of paper, etc., for they commonly seize such objects by their pointed ends. But with thin objects a certain number are drawn in by their broader ends. They do not act in the same unvarying manner in all cases, as do most of the lower animals.

The underlined word “unvarying” most nearly means __________.

Adapted from Volume Four of The Natural History of Animals: The Animal Life of the World in Its Various Aspects and Relations by James Richard Ainsworth Davis (1903)

The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort of surrounding. There are, however, numerous animals which possess the power of adjusting their color more or less rapidly so as to harmonize with a changing environment.

Some of the best known of these cases are found among those mammals and birds that inhabit countries more or less covered with snow during a part of the year. A good instance is afforded by the Irish or variable hare, which is chiefly found in Ireland and Scotland. In summer, this looks very much like an ordinary hare, though rather grayer in tint and smaller in size, but in winter it becomes white with the exception of the black tips to the ears. Investigations that have been made on the closely allied American hare seem to show that the phenomenon is due to the growth of new hairs of white hue. 

The common stoat is subject to similar color change in the northern parts of its range. In summer it is of a bright reddish brown color with the exception of the under parts, which are yellowish white, and the end of the tail, which is black. But in winter, the entire coat, save only the tip of the tail, becomes white, and in that condition the animal is known as an ermine. A similar example is afforded by the weasel. The seasonal change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.

The phrase “harmonize with,” underlined in the first paragraph, most closely means __________.

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

What can we infer from the author’s use of the underlined phrase, “sometimes, but not generally”?

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

The meaning of the underlined phrase “on the wing” is __________.

"Cacti" by Ami Dave (2013)

Cacti are plants suited to the desert and we must keep this factor in mind always when growing ornamental cacti in our gardens, for it helps in the survival of the plant. For example, a cactus should never be watered over its body as it will start to rot. This is because it is covered with a waxy coating which prevents water loss through evaporation. When one waters the cactus over its body, the waxy coating is washed away and the plant begins to rot. The amount of water that you must supply to the cactus is very much dependent upon the season and upon the climate of the place. During the summer season one should water cacti every four days whereas in the rainy season once every fifteen days is quite enough.

Cacti need a minimum of two and a half hours of sunlight per day. However they should not be kept all day in the sun because they may wrinkle in too much of bright sunlight. Unlike other plants cacti produce carbon dioxide during the day and oxygen during the night. Hence, they are ideal plants to be kept in bedrooms to freshen up the air at night.

If the cactus plant is to thrive and prosper, the size of the pot in which it is grown has to be carefully monitored. The pot should always be a little smaller than the plant itself because it is only when the plant has to struggle to survive that it will thrive. If the pot is too spacious the struggle element is removed and the chances are that the cactus will die. Cacti are like human beings. When they suffer they will grow. Similarly if a cactus shows no signs of growth, stop the watering. It should be resumed only when the plant resumes growth.

The substrata of a cactus pot is ideally composed of pieces of broken bricks at the bottom, charcoal above it, then coarse sand and pebbles above it. Leaf mould is the best manure.

Grafting of cacti is very simple. A very small piece of the cactus plant should be stuck with cellotape to the plant that needs grafting. The smaller the piece the easier it is to graft. To reproduce cacti, one has to simply cut off a piece of the cactus, allow it to dry for a few days and then just place it over the cacti substrate. It will automatically develop roots.

To differentiate between cacti and other plants that look like cacti is very easy. All cacti have fine hair at the base of each thorn. The so-called thorns are in fact highly modified leaves which prevent loss of water through transpiration. If one ever gets pricked by cacti thorns, one should take cellotape, place it over the area where the thorns have penetrated the skin and then peel it off. All the thorns will get stuck to the cellotape and will be removed.

If the author were to add the underlined sentences, "Cacti are like human beings. When they suffer they will grow," to the third paragraph, what would these lines mean in context?

"Abstraction in the Sciences" by Matthew Minerd (2014)

Thinking “abstractly” is not a term that means quite the same thing in all of the sciences. Although we rarely think about this, it plays a key role in almost all of our day-to-day thought. Consider a zoologist working in a lab with many animals. When she is studying any individual tiger, she is not completely worried about the particular tiger—at least not primarily. Instead, she is trying to figure out certain characteristics of tigers in general. By meticulous testing, the zoologist carefully works out the physiology of tigers and considers what are absolutely necessary elements of their physical makeup. Even when she places a tiger in different habitats, her sight is aimed at the general condition of tigers and their needs in general.

However, things become even stranger when you start to consider how we think about mathematical objects. Consider the case of geometric figures. A triangle appears to be rather simple for most of us to think about. You can draw a triangle on a piece of paper, each side having a certain thickness and length. However when you think about this in geometry class, the triangle’s edges have no real thickness. Neither a point nor a line has a thickness for the mathematician. Such a thickness only exists on our paper, which represents the point or line. Consider also a line drawn on a piece of graph paper. Technically, there are an infinite number of points in the line. Indeed, even between 4.5 and 4.6, there are an infinite number of numbers—for example 4.55 is between them, then 4.555 between 4.55 and 4.6, and 4.5555 between 4.555 and 4.6, et cetera. In all of these cases, the mathematical reality takes on a very peculiar character when you consider it in the abstract. However, the concrete triangle remains very tangible and ordinary. Likewise, 4.6 and 4.5 inches still have 0.1 inches between them. Nevertheless, in the abstract, mathematical realities are quite strange, even stranger then the idea of “a tiger in general.”

What is meant by the underlined selection, "Her sight is aimed at"?