单选题 It can be learned from the text that an assistant should offer you help

A、 as soon as you have entered the shop.
B、 just before you finish browsing.
C、 only when you have finished reading.
D、 when he leads you to a particular section.

【正确答案】 C

【答案解析】[注释] 细节理解题。本题问：从本文中知道，书店售货员应在何时向顾客提供帮助?第2
段第7句写道：“In a bookshop an assistant should remain in the background until you have finished browsing．Then，and only then，are his services necessary．”可见，[C]符合上述句意。