Nowadays people sometimes separate their waste to make it easier for it _______.
| A．reusing | B．to reuse | C．to be reused | D．reused |
In our class there are 60 students, of ____________ two thirds are boys.
| A．which | B．them | C．whom | D．who |
Mary wrote books to earn money while John gained his wealth _________ selling Mary’s works.
| A．on | B．by | C．in | D．through |
I hated it when people don’t ___________ their promises.
| A．carry out | B．look out | C．run out | D．find out |
________ hard he tried, he could not change his wife’s mind.
| A．However | B．Whatever | C．As | D．No matter what |
------I don’t know why he has made such a silly mistake in the exam.
------ He ____________ it before he handed in the paper.
| A．may have checked | B．might check |
| C．must have checked | D．should have checked |