When I lived with my roommates in the university, we ________ often talk into the night.

________ people used the computer thirty years ago, but now it’s very popular.

 ---Are you pleased with the result of the math exam?  ---Not at all. I can’t have ______ one.

---Where is Tom?        ---He hasn’t come to school today. I think he        be ill.

She is a quiet girl at school，but sometimes she _____ be very naughty.