题目内容
Trees ____ fight air pollution．They are natural air conditioners．| A．should | B．must | C．need | D．can |
D解析:
略
略
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Trees ____ fight air pollution．They are natural air conditioners．
| A．should | B．must | C．need | D．can |
题目内容
Trees ____ fight air pollution．They are natural air conditioners．| A．should | B．must | C．need | D．can |
Trees ____ fight air pollution．They are natural air conditioners．
| A．should | B．must | C．need | D．can |