When the winter _____ , all the construction works in northern China have to be stopped .
| A．sets off | B．sets out | C．sets aside | D．sets in |
I really don’t know for certain____ they discussed.this important event very secretly.
| A．where was it that | B．where it was that | C．where that | D．it was where that |
_____ you keep on working hard, I don’t mind whether you get good marks in your class.
| A．As long as | B．As soon as | C．As well as | D．as far as |
-----If I wasn’t busy., I could have been back by 5:30 o’clock.
----- What a pity! She____ here to see you.
| A．is | B．was | C．had been | D．has been |
They are determined to work out the task,____difficult it is.
| A．however | B．no matter what | C．no matter what | D．whatever |
I have to ____my diet rather than eat the same all the time.，so that I can keep fit.
| A．differ | B．vary | C．contiune | D．range |