(2013·成都第二次诊断)As the road to the airport is under reconstruction, we'd better ________ early to avoid the traffic jam.

Most of these groups _______ teachers and graduate students, but some freshmen join as well. 

 We recently did a simple experiment, which happens to ________ how children's knowledge of what a hero is like determines their behaviour.

As a war reporter in Iraq, Shui Junyi is ____ to many dangers.

Mr.Li has some trouble sleeping, so drinking a glass of milk before going to bed every night is his common