16．Mr·Brown gradual1y_________aknowledge of the subject．

A． required B． inquired C． achieved D． acquired

17．If I am not _________ when you come to my office，ask for my secretary．

A． suitab1e B． available C． comfortable D． proper

18．peasants supp1y workers with food， and workers________ supply peasants with manufactured goods．

A． in turn B． by turn C．for return D．by return

19．Let’s go out during the break to_________ our legs。

A． stretch B． expand C． move D． extend

20．I have just___________abeautiful poem in that little book.

A． come to B． come through C． come across D． come up

16.D 17.B 18.A 19.A 20.C