12.7 need/want/require/worth
?
  注意:當(dāng) need, want, require, worth(形容詞)后面接doing也可以表示被動。
   Your hair wants cutting. 你的頭發(fā)該理了。
   The floor requires washing. 地板需要沖洗。
   The book is worth reading. 這本書值得一讀。

典型例題
  The library needs___, but it'll have to wait until Sunday. 
A. cleaning  B. be cleaned  C. clean  D. being cleaned
  答案A. need (實(shí)意) +n /to do,need (情態(tài))+ do,當(dāng)為被動語態(tài)時(shí),還可need + doing. 本題考最后一種用法,選A。如有to be clean 則也為正確答案。
典:done,"不可能已經(jīng)"。must not do 不可以(用于一般現(xiàn)在時(shí))。