The global warming is more and more serious, for which human beings ______．
| A．are blaming | B．are to blame |
| C．are going to blame | D．are to be blamed |
Remember to __________ a good state of mind even if you should fail plenty of times.
| A．take up |
| B．brush up |
| C．get up |
| D．keep up |
Mary has __________ herself __________ for the party.
| A．held; up |
| B．attended; to |
| C．done; up |
| D．turned; up |
I __________ the names of plants.
| A．familiar with |
| B．are not familiar to |
| C．am not familiar as |
| D．am not familiar with |
The bus was due to __________ at 5 p. m.，but it arrived one hour late due to __________ by the heavy fog.
| A．arrive; be held up |
| B．arrive; being held up |
| C．arriving; be held up |
| D．having arrived; having been held up |
The professor devoted all his life __________ the treatment of AIDS.
| A．to research |
| B．in researching |
| C．to researching |
| D．at researching |