Each year in the United States, many black teenagers _______ of school, either because they cannot keep up or they have to work to support their family.

This diploma ( 毕业文凭 ) ________ that you have completed high school.

Hot metal ________ as it grows cooler.

过渡时期总路线的 “两翼”包括_______。

He ________ me that he decided to leave on Monday.