20. The rest of his life was devoted ___ pollution ___more happily .
| A．to prevent , to live | B．to protecting , from living |
| C．to protect , from living | D．to preventing , to live |
Although he was in poor health, Robert succeeded ______ other more famous engineers failed.
| A．which | B．that | C．what | D．where |
It was ________ Benazir Bhutto, former Pakistan prime minister, was leaving the rally(集会) that the suicide bomb happened, ________ the world felt sorry.
| A．when; for which | B．as; which |
| C．since; for which | D．after; which |
.---Where’s that report?
---I brought it to you ________ you were in Mr. Black’s office yesterday.
| A．if | B．when | C．because | D．before |
Pop music is such an important part of society_______ it has even influenced our language.
| A．as | B．that |
| C．which | D．where |
The research is so designed that once________nothing can be done to change it.
| A．begins | B．having begun |
| C．beginning | D．begun |