–Our classroom _________ twice a day. So it is very clean.–It is important for us to do this.

—Where ______cotton _____?—Oh，I don’t know.Let’s ask Mr Wu.

The sports meeting ________ twice a year in our school.

-How clean and tidy your bedroom is！ -Thank you. It ________ every day:

The young man was often seen _____ by the lake.