We looked everywhere for the keys but they are nowhere .A. to findB. to have foundC. to b

问题补充：

We looked everywhere for the keys, but they are nowhere .

A. to find

B. to have found

C. to be found

D. being found

答案：

A. to find

B. to have found

(答案→)C. to be found

D. being found

解析：因keys 与 find 是被动关系。