The air in Dongying is much worse than that in many other cities. We must do       to protect our environment. 

---Which do you like ____, Chinese, English or math? ---  English. 

––Has Mr Li known the news?––I’m afraid not. I called his house this morning but ____ answered.

-- Our school bus will leave at 8 o'clock tomorrow. Don't be late.-- OK. I will be there ten minutes________.

You will not be allowed to get into the plane_______ you pass security checks(安检).