—I’m sorry I stepped outside for a smoke. I was very tired.
—There is no______ for this while you are on duty.
| A．reason | B．excuse | C．cause | D．explanation |
As far as we know, Tom spends at least as much time watching TV as he _.
| A．does writing | B．writes | C．writing | D．does to write |
This is a story completely_____ by him, so don’t rust him.
| A．discovered | B．invented | C．found | D．known |
I can guess you were in a hurry. You _your sweater inside out.
| A．had worn | B．wore | C．are wearing | D．were wearing |
Historical experience can ____ as a most important source of information.
| A．serve | B．use | C．regard | D．prove |
--Who is the old man talking with your teacher?
---I don’t know. I _ him before.
| A．was never seeing | B．had never seen | C．never saw | D．wouldn’t see |