Mark has come in his raincoat and boots for rain.A. preparingB. preparedC. to prepareD.

问题补充：

Mark has come in his raincoat and boots, for rain.

A. preparing

B. prepared

C. to prepare

D. prepares

答案：

A. preparing

(答案→)B. prepared

C. to prepare

D. prepares

解析： 本句中考察的动词prepare的过去分词转换的固定搭配be prepared for..为…做好准备；如果选择A项，后面就不应该有介词for的搭配，因为prepare是一个及物动词。句义：他穿着雨衣和靴子进来了，已经为下雨做好了准备。故B正确。