This is not an economical way to get more water; _________,it is very expensive.
| A．on the contrary | B．on the other hand | C．in a word | D．rather than |
The time is drawing near_____food raised in space will directly benefit humans below.
| A．where | B．when | C．whether | D．why |
．Play, often seen as______ activity for kids, is still important in____development of teenagers.
| A．the; the | B．an; the | C．an; 不填 | D．the; 不填 |
A big step____to strengthen China’s health care systems since we launched an effort in 2008.
| A．has been taken | B．is being taken | C．was taken | D．had been taken |
．---Let me help you cross the street.--______! I’m not that old.
| A．Take your time | B．No way | C．Come on | D．Go ahead |
We went into a hall, on_____ walls hung a few pictures of some famous scientists.
| A．its | B．which | C．whose | D．those |