Paragraph 1: Groundwater is the word used to describe water that saturates the ground, filling all the available spaces. By far the most abundant type of groundwater is meteoric water; this is the groundwater that circulates as part of the water cycle. Ordinary meteoric water is water that has soaked into the ground from the surface, from precipitation (rain and snow) and from lakes and streams. There it remains, sometimes for long periods, before emerging at the surface again. At first thought it seems incredible that there can be enough space in the “solid” ground underfoot to hold all this water.
1. Which of the following can be inferred from paragraph 1 about the ground that we walk on?
○It cannot hold rainwater for long periods of time.
○It prevents most groundwater from circulating.
○It has the capacity to store large amounts of water.
○It absorbs most of the water it contains from rivers.
2. The word “incredible” in the passage is closest in meaning to
Paragraph 2: The necessary space is there, however, in many forms. The commonest spaces are those among the particles—sand grains and tiny pebbles—of loose, unconsolidated sand and gravel. Beds of this material, out of sight beneath the soil, are common. They are found wherever fast rivers carrying loads of coarse sediment once flowed. For example, as the great ice sheets that covered North America during the last ice age steadily melted away, huge volumes of water flowed from them. The water was always laden with pebbles, gravel, and sand, known as glacial outwash, that was deposited as the flow slowed down.
3. The word “out of sight” in the passage is closest in meaning to
4. According to paragraph 2, where is groundwater usually found?
○Inside pieces of sand and gravel
○On top of beds of rock
○In fast rivers that are flowing beneath the soil
○In spaces between pieces of sediment
5. The phrase “glacial outwash” in the passage refers to
○the huge volumes of water created by glacial melting
○the particles carried in water from melting glaciers
Paragraph 3: The same thing happens to this day, though on a smaller scale, wherever a sediment-laden river or stream emerges from a mountain valley onto relatively flat land, dropping its load as the current slows: the water usually spreads out fanwise, depositing the sediment in the form of a smooth, fan-shaped slope.
Sediments are also dropped where a river slows on entering a lake or the sea, the deposited sediments are on a lake floor or the seafloor at first, but will be located inland at some future date, when the sea level falls or the land rises; such beds are sometimes thousands of meters thick.
6. All of the following are mentioned in paragraph 3 as places that sediment-laden rivers can deposit their sediments EXCEPT
○A mountain valley
○A lake floor
Paragraph 4: In lowland country almost any spot on the ground may overlie what was once the bed of a river that has since become buried by soil; if they are now below the water’s upper surface (the water table), the gravels and sands of the former riverbed, and its sandbars, will be saturated with groundwater.
7. The word “overlie” in the passage is closest in meaning to
Paragraph 5: So much for unconsolidated sediments. Consolidated (or cemented) sediments, too, contain millions of minute water-holding pores. This is because the gaps among the original grains are often not totally plugged with cementing chemicals; also, parts of the original grains may become dissolved by percolating groundwater, either while consolidation is taking place or at any time afterwards. The result is that sandstone, for example, can be as porous as the loose sand from which it was formed.
8. The phrase “So much for” in the passage is closest in meaning to
○that is enough about
○now let us turn to
○of greater concern are
○this is related to
9. The word “plugged” in the passage is closet in meaning to
Paragraph 6: Thus a proportion of the total volume of any sediment, loose or cemented, consists of empty space. Most crystalline rocks are much more solid; a common exception is basalt, a form of solidified volcanic lava, which is sometimes full of tiny bubbles that make it very porous.
Paragraph 7: The proportion of empty space in a rock is known as its porosity. But note that porosity is not the same as permeability, which measures the ease with which water can flow through a material; this depends on the sizes of the individual cavities and the crevices linking them.
10. According to paragraphs 6 and 7, why is basalt unlike most crystalline forms of rock?
○It is unusually solid.
○It often has high porosity.
○It has a low proportion of empty space.
○It is highly permeable.
11. What is the main purpose of paragraph 7?
○To explain why water can flow through rock
○To emphasize the large amount of empty space in all rock
○To point out that a rock cannot be both porous and permeable
○To distinguish between two related properties of rock
Paragraph 9: The relative amount of these two kinds of water varies greatly from one kind of rock or
sediment to another, even though their porosities may be the same. What happens depends on pore size. If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.
12. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
○Surface tension is not strong enough to retain drops of water in rocks with large pores but it strong enough to hold on to thin films of water in rocks with small pores.
○Water in rocks is held in place by large pores and drains away from small size pores through surface tension.
○Small pores and large pores both interact with surface tension to determine whether a rock will hold water as heavy drops or as a thin film.
○If the force of surface tension is too weak to hold water in place as heavy drops, the water will continue to be held firmly in place as a thin film when large pores exist.
Paragraph 8: Much of the water in a sample of water-saturated sediment or rock will drain from it if the sample is put in a suitable dry place. But some will remain, clinging to all solid surfaces. It is held there by the force of surface tension without which water would drain instantly from any wet surface, leaving it totally dry. The total volume of water in the saturated sample must therefore be thought of as consisting of water that can, and water that cannot, drain away.
13. Look at the four squares that indicate where the following sentence could be added to the passage.
What, then, determines what proportion of the water stays and what proportion drains away?
Where would the sentence best fit?
14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Much of the ground is actually saturated with water.
○Sediments that hold water were spread by glaciers and are still spread by rivers and streams.
○Water is stored underground in beds of loose sand and gravel or in cemented sediment.
○The size of a saturated rock’s pores determines how much water it will retain when the rock is put in a dry place.
○Groundwater often remains underground for a long time before it emerges again.
○Like sandstone, basalt is a crystalline rock that is very porous.
○Beds of unconsolidated sediments are typically located at inland sites that were once underwater.
1. 以ground作为关键词定位至全段最后一句，说At first sight土地是不可能有那么大的空间去容纳这些水的，at first sight第一眼看上去的意思是这个不是事实，而且事实刚好与这个相反，也就是说土地是有空间的，所以C正确
2. incredible令人难以置信的，想到credit card信用卡，credit指的是信用或者学分ible或者able表示可以……的，credible可信的，incredible难以置信的，不知道的话看上题也知道是不可能
3. out of sight表面意思就是在视野之外，也就是看不见， C和D都说看见，所以错。而且far away离得很远也不一定就看不见，所以也不对。不知道的话说beneath the soil在土下面，当然也是看不见之意，所以B正确
4. 问的是地下水在哪儿最经常在哪儿发现，找到第二句中的the commonest spaces are……最常见的地方是blablabla，这个blablabla就是我们要的答案。在那些颗粒之间的空隙里，所以首先正确的答案应该是space，答案D是正确的
5. glacial是冰川的，与冰川有关的，outwash是个合成词，表面意思就是冲出来的，不知道的读原文，原文说pebble, gravel and sand, known as glacial outwash，也就是说前面的三个都叫做glacial outwash，其中sand是一定知道的，不是水，所以AC错，更不是冰，B错，应该是包括沙子在内的一堆小颗粒
6. 排除题，可在第一句找到flat land，在第二句的前半句Sediments are also dropped where a river slows on entering a lake or the sea找到C和D，A虽然有说到，但不是沉积物沉积的地点，所以要选的答案是A
8. so much for表面意思就是已经很多了，也就是足够的意思，代入原文，说unconsolidated未固结的沉积物已经说了很多了，下面就说说固结的沉积物了，所以A正确，B和C都说我们马上要讨论的是未固结的沉积物，所以说反了；D表示与……相关，完全不沾边，错
9. plug的意思是插入，填满。原文说原来颗粒之间的空隙没有被混凝土怎么样，而前一句说固结的沉积物之间有很多能够存水的空隙，既然是有空隙，就说明没被填满，所以答案是filled up，A洗B拖曳D浸透都不沾边
10. 以crystalline rock和basalt为关键词定位至第六段的最后一句，原文说大部分crystalline rock是固化比较好的，但basalt是个例外，说basalt更加porous，孔隙率更高，所以B正确
13. 待插入句说多少流走多少剩下是什么决定的，所以之前必须得说一部分流走了一部分剩下了，原文最后一句才说到这个，所以D是答案。貌似B选项之前也说了流走和剩下，但B之后有个it is held there，这个it指的是前文的留下来的水，所以与上文过渡紧密，不能插入句子。