Where is your sister?—–She _________ my mom with cooking.

Lucy is good _____ English while Lily does well _____ Chinese. [ ]

I didn’t see you when I went to your office yesterday afternoon. Where were you?—I ____ a meeting in the meeting room.

Has Sam finished his report?—I have no idea. He _______ it in his office the whole morning.

The teachers ________ on the blackboard with chalk in the future.