You’d better book the tickets as early as possible they will be sold out soon. A. andB.

问题补充：

You’d better book the tickets as early as possible, they will be sold out soon.

A. and

B. but

C. so

D. or

答案：

A. and

B. but

C. so

(答案→)D. or

解析：

试题分析: 句意：你最好尽早订票，否则不义就卖光了。and并且，but但是，so所以， or否则。had better最好，后接动词原形；book预订；as early as尽早；sold out卖完；根据语境可知答案选D.