They ______ on the program for almost one week before I joined them, but still no good results _______ so far.
| A．had worked ; come out | B．have worked ; came out |
| C．had been working ; have come out | D．have been working ; have come out |
Historically, __________main material for making tables has been wood, but__________metal and stone have also been used.
| A．the; the | B．the; / | C．/; the | D．/ ; / |
．______two articles to write today，I have to stay at the classroom to make it.
| A．With | B．For | C．Because of | D．As for |
----_____is it that is troubling Mary ?
----Working out the maths problem..
| A．What | B．How | C．Why | D．Which |
I wonder how long it will take you_____ such a hard task within so little time.
| A．complete | B．to complete | C．completing | D．completed |
Tom was absent from school this morning, because sometimes he was a little weak and could ______ill .
| A．take | B．set | C．catch | D．fall |