— Mum, my friends are waiting for me outside. May I go out to play with them?— Yes, you        , but be careful, please.

 ---I saw Mr. Smith at Xianyang Airport this morning.  ---You ____. He’s still on holiday in Hawaii.

Don't blame such a small boy any more. Even the wisest___ make a mistake sometimes.

 I’m really tired of Tom because he ______ keep asking silly questions. 

 Personally, the job as a teacher _____ be challenging, for I sometimes _____ deal with some smarter but less diligent students.