Dalton wondered why the heavier and lighter gases in theatmosphere did not separate as oil and water do.He finallyconcluded that the constituent 1 _must exist in the form of 2_particles or atoms and that these 3_ be completely mixedtogether in the 4 _.This threw a new light in 5_ laws of definiteproportions.It was 6_ necessary to suppose that the atoms 7 _combinesintossmall groups of uniform 8_ and so form morecomplex substance; 9_ the mystery of this law was 10_ .Daltonsuggested, for example, that carbon monoxide 11_ formed bythe one with one 12_ of atoms ofcarbon and oxygen, 13_ carbon dioxide results from a single 14_ of carbon uniting with twoatoms 15 _ oxygen.Assuming this to be true, 16_ the definite proportions of Prout’s law (17_ allchemical compounds the different constituents 18_ enter in unvarying proportions) wouldnaturally 19_ the relative weights of the many 20 _kinds of atoms.
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.wouldn’t C.always D.never
19.A.describe B.unit C.mix D.reveal
20.A.different B.usual C.important D.chemical
