_____you’ve made a promise, you are expected to carry it out.
| A．While | B．Unless |
| C．Once | D．Though |
How long did it take them to get ___ this river?
A.through B,over C.across D.till
This is an illness that can result in total blindness ________ left untreated.
| A．after | B．if |
| C．since | D．unless |
— We want someone to design the new art museum for us.
— ________ the young fellow have a try?
| A．May | B．Shall |
| C．Will | D．Need |
The little boy is dirty from head to foot because he ________ in the mud all morning.
| A．has played | B．is playing |
| C．has been playing | D．was playing |
So many directors ________, the board meeting had to be put off.
| A．were absent | B．been absent |
| C．had been absent | D．being absent |