There are so many kinds of pens in the shop I can’t decide .A. when to buyB. where to buy

问题补充：

There are so many kinds of pens in the shop ,I can’t decide .

A. when to buy

B. where to buy

C. what to buy

D. which to buy

答案：

A. when to buy

B. where to buy

C. what to buy

(答案→)D. which to buy

解析：根据前半部分的意思“商店中有如此多的钢笔”可知，后半句的意思应该是“我不能决定选哪一枝”。ABC都与题干的意思不符，所以本题选D。