单选题：If you are too formal, people around you won't be _____. [..

He's given me so much help that I really want to do something for him _____. [ ]A. in returnsB. by turns C. in return D. in answer

He wants to see changes in the company and I am sure he will ______. [ ]A. on time B. at a time C. at one time D. in time

The old man has devoted half his life _____ helping the weak. [ ]A. of B. to C. by D. for

I don't think Tom's remarks are _____; he is not supposed to say so. [ ]A. in peace B. in place C. in trouble D. in surprise

I don't think it was an accident at all. Your brother did it _____. [ ]A. for purpose B. on purpose C. in order D. by chance