What the science teacher does andsays ____ of great importance to college students.

How long _________ in singapore?— For just the weekendI’ll be back next Monday morning

____ H1N1 flu from spreading, our government has taken some effective measures. [ ]

Air quality in our city is becoming worse and worse. —Yes. These days’ PM2.5 readings are frightening.We must do something to ______air pollution.

I lost sight of Wang Ping when we reached _____ lookedlike a large market because of too many carriages flying in all directions.