A good teacher must be able to hold his students’ attention ____ he reaches the end of the class.
| A．when | B．after | C．until | D．unless |
More and more rich people have promised to ______ their wealth after death to help the poor and the disabled.
| A．give away | B．give up | C．give out | D．give off |
Don't blame such a small boy any more. Even the wisest___ make a mistake sometimes.
| A．must | B．can | C．should | D．shall |
A red light will start continuously flashing when the batteries____ low.
| A．get | B．will get | C．are getting | D．got |
I’m sorry I didn’t phone you, but I’ve been very busy_____ the past couple of weeks.
| A．beyond | B．with | C．among | D．over |
The science of computer,____ rapid progress has been made, is the most important of all.
| A．to which | B．from which | C．in which | D．of which |