The police the lost boy everywhere when he suddenly turned up in a supermarket.A. search

问题补充：

The police the lost boy everywhere when he suddenly turned up in a supermarket.

A. searched

B. searched for

C. was searching

D. were searching for

答案：

A. searched

B. searched for

C. was searching

(答案→)D. were searching for

解析：考查时态。根据句意可知是在他突然再现的时候，这个过去的某个时间点上，正在进行，正在发生的事情。所以使用过去进行时。