han twenty years____________since hecame to teach in this school, and every student and every parent_____him.

call me at 9:00 o’clock tomorrow morning ,when Ia lecture atHarvard.

Don’tworry Intelligent students can always ­­­­­­­­­_______ good solutions toproblems

下列各句中，没有语病的一句是（ ）

Every one of us must know this: _________ we live can we save the earth．