31.（单选题）Everyone should _______ his/her duty to help the company.

A. A.not until

B. B.as long as

C. C.the moment

D. D.only if

A. A.was sinking

B. B.has sunk

C. C.were to sink

D. D.sunk

A. A.commerce

B. B.commercialize

C. C.commercial

D. D.commercially

A. A.Had I known; would ring him up

B. B.Should I know; would have rung him up

C. C.If I knew; would ring him up

D. D.Had I known; would have rung him up

A. A.Which

B. B.What

C. C.That

D. D.Why

A. A.At

B. B.To

C. C.For

D. D.With

A. A.consists in

B. B.consists of

C. C.makes up

D. D.makes from

A. A.事实上，我最感谢你对我的帮助。

B. B.的确，我非常感谢你对我的帮助。

C. C.事实上，我非常感谢你对我的帮助。

D. D.真的，我非常感谢你对我的帮助。