The water of the lake was so __________ that it looked like glass.

I think students should have mobile phones to call their parents.— ________. They often use them to play games instead.

You had better take something to read whenyou go to see the doctor____ you have to wait.

I visited many places including the History Museum last Saturday. When I _______ at the hotel, it was very late.

Do you often go to the Youth Centre—I , but I have no time now.