．Elephants, which are the largest mammals on the earth, have almost no natural enemies ______ human beings.
| A．rather than | B．other than | C．more than | D．less than |
____ to America, her parents have not heard from her.
| A．Because she went | B．After she went | C．When she went | D．Since she went |
It looks ____ it's going tosnow.
| A．that | B．as | C．as if | D．like that |
The size of the audience,____ is expected, is more than thirty thousand.
| A．as | B．what | C．that | D．whom |
John did the task____ his sister.
| A．as good as | B．as better as | C．as well as | D．as best as |
_____ he had not been ill , Tom would have won the race.
| A．Unless | B．As | C．If | D．Until |