专四 英语 完形填空

9.

Dalton wondered why the heavier and lighter gases in the atmosphere did not separate as oil uniform so form more complex substance; the mystery of this law was .Dalton suggested, for example, that carbon monoxide formed bythe one with one atoms of compounds the different constituents in unvarying proportions) would naturally the 1.A.gases B.pieces C.things D.gas

2.A.timely

3.A.ought B.trimmed C.tiny D.topical B.could C.will D.must

4.A.sky B.atmosphere C.oxygen D.environment

5.A.various B.many C.the

C.that D.those 6.A.only B.too

7.A.should D.extremely D.could B.were C.get

8.A.construct B.structure

9.A.but B.also C.thus C.piece D.feature 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

14.A.piece

15.A.from B.when C.therefore B.type D.also C.atom D.measure B.in C.of D.for

16.A.then B.so C.by D.that

17.A.from B.in C.to D.for

C.always D.never

C.mix D.reveal 18.A.are B.wouldn’t 19.A.describe B.unit

20.A.different ual C.important D.chemical