A: Listen! Is it Tina singing in the next room?B: No, it __________ be her. She is still in Shanghai.

He____know the answer, but I’m not sure.

The lady in the sitting room           be over sixty. She looks so young.

You’d better put on a heavy coat.Sometimes it________be very cold here at night.

 .Susan’s parents have bought a large house with a swimming pool. It ______be very expensive.