I know one of the things I was unsure about was _____hard it would be to climb this mountain

Please ______ your disgraceful conduct during the ball!—I’m sorry. I was totally out of my mind.

It is the ability to do the job, not where you came from or what you are_____ matters.

________students took the high school entrance exam on time ________ the morning of June 16th in Yancheng , though it rained heavily .

As we all know, the Silk Road _______ China to the west in ancient times.