He tried his best to solve the problem, _______difficult it was.
| A．however | B．no matter | C．whatever | D．although |
Some people waste food，________other people haven’t got enough to eat.
| A．when | B．until | C．since | D．while |
Look! The houses _________.
| A．is being built | B．are building | C．being built | D．are being built |
The stamps were ________ according to their styles and features.
| A．found out | B．sorted out | C．put out | D．taken out |
I can’t give my son the leading position. ______, he is too young; secondly, I want Mr. Smith to have the job.
| A．After all | B．First of all | C．Above all | D．In all |
With no one to________ in such a frightening situation，she felt very helpless.
| A．turn to | B．turn on | C．turn off | D．turn over |