A man does not know the difficulty of anything_________ he does it personally.
| A．although | B．if | C．because | D．Unless |
The Arabian Nights____ well known to English lovers.
| A．is being | B．are | C．were | D．is |
Over 80 percent of the population _____ workers.
| A．will be | B．are | C．is | D．was |
A professor and writer ____ present at the meeting last night.
| A．had been | B．were | C．is | D．was |
The boy at the back is the only one of the students who _____ from Africa in our school.
| A．was | B．were | C．is | D．are |
It is not I but you who ______ the first to run to the goal in that competition.
| A．is | B．was |
| C．are | D．is going to |