Question

Customers are asked to make sure that they ________ the right change before leaving the shop.

A. will give
B. have been given
C. have given
D. will be given

Answer 1

答案B
give后接双宾语，the right change作直接宾语，customers作间接宾语，所以当customers作主语时，其谓语动词要用被动语态；before leaving the shop表示在离开商店前，与现在完成时连用，表示在这之前已经完成的动作。