Be careful . You _______ cross the road when the traffic light is red . The traffic is heavy at this time of day .

I hear that Lily’s brother is a worker here.—Look, the man _________ is working over there is her brother.

The piano sounds .I want to leave now. Where is the exit(出口)?

________ are you? I’m thirteen ________.[ ]

Listen! Is Mary singing in the next room?—No. It _______ be Mary．She has gone to Shanghai for an important meeting.