I called you up last night but I couldn’t _____________.

It’s unwise of you not to       his suggestions, for he is an authority in this field.

Our English teacher often creates a(n)      in class for us to communicate like native speakers

You’d better_  your scores and see if you have passed the exam.                       

Although we haven’t got the accurate statistics, it is estimated that ______ 300 factories in this province closed down during the economic crisis.