Question

【題目】Potatoes turn green when ________ to light.

A. exposed B. are exposed

C. being exposed D. to be exposed

Answer 1

【答案】A

【解析】

試題分析：考查非謂語動詞。be exposed to遭受，暴露于…，這里的exposed可以看作 when they are exposed to the light的省略。因?yàn)榫渥又杏衱hen,while等這些詞時(shí)，從句可以省略與主句相同的主語和be動詞。是使顯露的意思。故選A。