The reason _____ their failure you know is ______ they didn’t get fully prepared for the experiment.
| A．why…that | B．that…why |
| C．why…because | D．for…that |
I know Mr Brown；we _____ to each other at an international conference.
| A．are introduced | B．have been introduced |
| C．were introduced | D．had been introduced |
We _____ with you for the time being.
| A．will stay | B．will be staying | C．would stay | D．have stayed |
—Who sings best in your class?
—Mary _____.
| A．is | B．does | C．do | D．sing |
She _____ her pen in her room now.
| A．finds | B．is finding | C．looks for | D．is looking for |
What _____ you _____ tomorrow morning?
| A．are/going to do | B．are/doing | C．are/done | D．have/done |