24. You ought to have put the milk in the refrigerator, and now sour.
A. it smell
B. it is smelt
C. it smells
D. it is smelling
网友回答
A. it smell
B. it is smelt
(答案→)C. it smells
D. it is smelling
解析：考查时态。句意：你应该已经把牛奶放进冰箱了，可是现在闻起来酸了吧！结合语境可知下文描述的是现在客观存在的状态，故用一般现在时态，选C。