Fighting an artificial greenhouse effect seems to be the greatest of environmental challenges, ________？
| A．isn't it | B．does it |
| C．doesn't it | D．is it |
Tom said that he was late because he ________ in the elevator.
| A．got trapped | B．trapped |
| C．got lost | D．lost |
His parents told him ________ too much about what others said.
| A．don’t care | B．not care |
| C．to not care | D．not to care |
________ his appearance, he is most probably a new teacher.
| A．Judging with | B．Judging from |
| C．Going through | D．Going over |
After teaching in Bejing for five years, he returned to the small town ________ he grew up as a child.
| A．where | B．when | C．which | D．that |
He devoted all his life to ________ those who are suffering from cancer.
| A．helping | B．help |
| C．be helped | D．being helped |