4、Professor Peterson was invited to give a speech at a conference held for the top () at Fortune 500 companies.

6、Our old classroom building, which was built a century ago, has become a sort of a local ().

5、“Do fish () each other?” “Yes. At least many of them do.”

4、() in decades, the leaders of the two nations shook hands and sat down to talk.

3、When you make travel plans, you’d better () that every flight can be late.