---How long has the train been away?---Sorry. I don’t know. By the time I got here, the train ________.
---water do we need to drink to keep healthy every day? ---Study shows that eight glasses should be enough.
---If we take environment problems seriously, the earth worse and worse. ---I agree.
I’m good at English,and I want to learn ____ foreign language.
---When will you start school? ---I’m not quite sure. Maybe three weeks.
It’s possible_____ the old. We should often do so.