Smog
1 The oxidation of exhaust gases is one of the primary sources of the world's pollution. The brown haze that is poised over some of the world's largest cities is properly called photochemical smog; it results from chemical reactions that take place in the air, using the energy of sunlight. The production of smog begins when gases are created in the cylinders of vehicle engines. It is there that oxygen and nitrogen gas combine as the fuel burns to form nitric oxide (NO), a colorless gas. The nitric oxide is forced out into the air through the vehicle tailpipe along with other gases.
2 When the gas reaches the air, it comes into contact with available oxygen from the atmosphere and combines with the oxygen to produce nitrogen dioxide (NO2), which is a gas with a brownish hue. This nitrogen dioxide plays a role in the formation of acid rain in wetter or more humid climates and tends to decompose back into nitric oxide as it releases an oxygen atom from each molecule; the released oxygen atoms quickly combine with oxygen (O2) molecules to form ozone (O3). The brownish colored nitrogen dioxide is partially responsible for the brown color in smoggy air; the ozone is the toxic substance that causes irritation to eyes.
1. The word poised in paragraph 1 is closest in meaning to
(A) interacting
(B) sitting
(C) blowing
(D) poisoning
2. The phrase take place in paragraph 1 is closest in meaning to
(A) position themselves
(B) put
(C) are seated
(D) occur
3. The word forced in paragraph 1 could best be replaced by
(A) obliged
(B) required
(C) pushed
(D) commanded
4. The word hue in paragraph 2 is closest in meaning to
(A) color
(B) odor
(C) thickness
(D) smoke
5. The phrase plays a role in in paragraph 2 is closest in meaning to
(A) makes fun of
(B) serves a function in
(C) acts the part of
(D) moves about in
参考答案：BDCAB
Parasitic plants
1 Parasitic plants are plants that survive by using food produced by host plants rather than by producing their own food from the Sun's energy. Because they do not need sunlight to survive, parasitic plants are generally found in umbrageous areas rather than in areas exposed to direct sunlight. Parasitic plants attach themselves to host plants, often to the stems or roots, by means of haustoria, which the parasite uses to make its way into the food channels of the host plant and absorb the nutrients that it needs to survive from the host plant.
2 The world's heaviest flower, a species of rafflesia, is a parasite that flourishes among, and lives off of, the roots of jungle vines. Each of these ponderous blooms can weigh up to 15 pounds (7 kg) and can measure up to 3 feet (1m) across.
11. The word umbrageous in paragraph 1 is closest in meaning to
(A) moist
(B) well lit
(C) shaded
(D) buried
12. Haustoria in paragraph 1 are most likely
(A) offshoots from the parasite
(B) seeds of the host plant
(C) fruits from the host plant
(D) food for the parasite
13. The phrase make its way into in paragraph 1 is closest in meaning to
(A) develop
(B) penetrate
(C) outline
(D) eat
14. The word ponderous in paragraph 2 is closest in meaning to
(A) smelly
(B) hidden
(C) mature
(D) heavy
15. The word across in paragraph 2 could best be replaced by
(A) in diameter
(B) on the other side
(C) at a distance
(D) inside and out
参考答案：CABDA |
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