1.A.gases B.pieces C.things D.gas
2.A.timely B.trimmed C.tiny D.topical
3.A.ought B.could C.will D.must
4.A.sky B.atmosphere C.oxygen D.environment
5.A.various B.many C.the D.those
6.A.only B.too C.that D.extremely
7.A.should B.were C.get D.could
8.A.construct B.structure C.piece D.feature
9.A.but B.also C.thus D.nevertheless
10.A.solved B.discovered C.broked D.told
11.A.must B.been C.were D.is
12.A.putting B.pairing C.placing D.preparing
13.A.while B.when C.therefore D.also
14.A.piece B.type C.atom D.measure
15.A.from B.in C.of D.for
16.A.then B.so C.by D.that
17.A.from B.in C.to D.for
18.A.are B.wouldnt C.always D.never
19.A.describe B.unit C.mix D.reveal
20.A.different B.usual C.important D.chemical
Cloze Test 32
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】C
【解析】根据句子意思判断,句中的词意为微粒的意思，选项C.tiny合乎题意。
3.【答案】D
【解析】情态动词must在这里是“必定、必须”的意思。
4.【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。
