Question

【题目】_______ not necessary, booking in advance is recommended in order to avoid waiting in line.

A. Once B. Since

C. If D. While

Answer 1

【答案】D

【解析】考查连词。once“一旦”；since“自从；由于”；if“如果”；while“在……期间；尽管”。结合句意， “尽管没有必要，人们还是建议提前订票以避免排队等候”，故选D项。