______ time ______, what the scientist said finally proved to be true.
| A．With; went by | B．With; going by |
| C．As; goes by | D．As; going by |
Not until he met with the difficulty _______ the importance of group work.
| A．he realized | B．did he realize | C．realized he | D．he didn’t realize |
Mary got the first prize in the National Math Competition, ________, for sure, delighted everyone.
| A．who | B．that | C．this | D．which |
______ he had broken the record, he would be a world-famous runner now.
| A．When | B．Because | C．If | D．Though |
—Was the driving pleasant when you vacationed in Mexico last summer?
—No, it _______ for four days when we arrived, so the roads were very muddy.
| A．has rained | B．had been raining | C．rained | D．has been raining |
Why not stay at home ________ the road is so slippery after the heavy snow?
| A．in case | B．as long as | C．now that | D．even if |