— How about buying Sam a mobile phone? After all, he isn’t a boy any more. —I think it necessary, for we sometimes want to make sure if he _______ home for dinner.
The entire hall burst into a great cheer and applause _______ the Nobel Prize winner appeared on the stage accompanied by the chairman.
John has determined to _______ teaching in the quake-hit area when he graduates from university.
------You’ve left the light on. ------Oh, so I have. _____________to turn it off.
--How did she get infected? --She ________the virus without any protection.
He always did well at school __________ having to do part-time jobs every now and then.