You were silly not ________ your car．

A.to lock

B.to have locked

C.locking

D.having locked

答案及解析： B

解析：

句子使用“主语+be+adj．+to do”，所以排除C, D两项，were说明动作发生在过去，且lock的动作发生在were之前，所以用不定式完成式。