Question

One evening when it was swarm, I stayed awake ___________ until half past eleven in order to have a good look at the moon by myself.

A．on average

B．on purpose

C．on sale

D．on schedule

Answer 1

B

试题分析：on average通常，平均；on purpose有目的地；on sale廉价出售；on schedule按时。句意：一天晚上我一直故意没有去睡觉，直到晚上11:30，为了自己去看看月亮。根据句意故选B。
点评：本题难度适中。介词短语也是高考的热点，需要考生平时多积累，注意它们的用法及区别。
即学即练：He could have finished it __________, but somehow he fell behind.
A. on average        B. on purpose        C. on sale         D. on schedule
解析：D。句意：他原本能按预定进度做完这件事的，但不知怎地却落后了。