Dalton wondered why the heavier and lighter gases in the atmosphere did not separate as oil and water do. He finally concluded that the constituent __1__ must exist in the form of tiny particles or atoms and that these must be completely mixed together in the __2__. This threw a new light in the laws of definite proportions. It was __3_ necessary to suppose that the atoms could combines into small groups of uniform __5__ and so form more complex substance; thus the mystery of this law was __5__ . Dalton suggested, for example, that carbon monoxide __6__ formed by the one with one pairing of atoms of carbon and oxygen, __7_ carbon dioxide results from a single atom of carbon uniting with two atoms __8__ oxygen. Assuming this to be true, then the definite proportions of Prout′s law would naturally __9_ the relative weights of the many __10__ kinds of atoms.
1. A. gases B. pieces C. things D. gas
2. A. sky B. atmosphere C. oxygen D. environment
3. A. only B. too C. that D. extremely
4. A. construct B. structure C. piece D. feature
5. A. solved B. discovered C. broke D. told
6. A. must B. been C. were D. is
7. A. while B. when C. therefore D. also
8. A. from B. in C. of D. for
9. A. describe B. unit C. mix D. reveal
10.A.different B. usual C. important D. chemical
1.【答案】A
【解析】根据上文中的heavier and lighter gases可以确定, 本空中应填入“组成的气体”，即constituent gases。
2.【答案】B
【解析】sky意为“天空”，atmosphere意为“大气”, oxygen意为“氧气”, environment意为“环境”,只有B项正确。
3.【答案】A
【解析】only necessary的意思是“仅仅是必要”。故A正确。
4.【答案】B
【解析】根据句子意思判断,这里需要“结构”这个词，而B合乎题意。
5.【答案】A
【解析】solve相当于find a solution or an answer to, 意为“解决”、“解开”,如: solve a problem (a puzzle, a mystery)；discover相当于find something existing but not known before, 意为“发现”,如: discover a place (a fact, the truth)。因此应选A。
6.【答案】D
【解析】因为是表一般规律，又是单数，所以用is这个词。
7.【答案】A
【解析】while表示对比。如：Some substances are soluble, while others are not.一些物质是可溶的，而另一些物质是不可溶的。
8.【答案】C
【解析】of表示“含量，分量”。
9.【答案】B
【解析】describe意为“描述”；unite意为“结合，合并”；mix意为“(不同的东西)混合在一起”，如：mix flour and water；reveal意为“揭露，揭示”
10.【答案】A |
