When did China __ the first man-made satellite to circle the earth, do you know?

30. — Whyyou be talking so loudly while others are studying?– I am terribly sorry.

Is this the second time that you _________ the Summer Palace?[ ]

b, ______ as a manager for many years,found it hard to be an ordinary clerk again.

He is going to build a team that has a lot of potential and he thinks that is ____ excites him.