You should be a diet; otherwise you will get fatter and fatter.A. atB. inC. onD. with

问题补充：

You should be a diet; otherwise you will get fatter and fatter.

A. at

B. in

C. on

D. with

答案：

A. at

B. in

(答案→)C. on

D. with

解析：考查介词：be on a diet节食，句意：你应该节食，否则会越来越胖的。选C。