—Would you like _______ , sir?    —No, thanks. I have had much.

Look , dark clouds are gathering. It is ________to rain.

Is Mr. Wang good at drawing his students into ______    discussion?

However，at　times　this　balance　in　nature　is＿＿，resulting　in　anumber　of　possibly　unforeseen　effects．

—Do you think our teacher is ________ ？—Yes， he always corrects our homework and prepares his lessons　_______.