—Must I take part in the activity?—No, you _______. You’re too young. You should look after yourself.
What do you usually doweekends?
—Hi. _______________. ----Yes. It’s been a long time.
Tom ______ watch TV after supper _____ last night.
I ______ ride a bike to school. But this morning I took a taxi because I got up late.
Twenty percent of the water ______ from the underground(地下).