15.4 谓语需用单数
 
1) 代词each和由every, some, no, any等构成的复合代词作主语,或主语中含有each, every, 谓语需用单数。
  Each of us has a tape-recorder.
  There is something wrong with my watch.

2) 当主语是一本书或一条格言时,谓语动词常用单数。
  The Arabian Night is a book known to lovers of English.
  <<天方夜谭>>是英语爱好者熟悉的一本好书。

3) 表示金钱,时间,价格或度量衡的复合名词作主语 时,通常把这些名词看作一个整体,谓语一般用单数。(用复数也可,意思不变。)
  Three weeks was allowed for making the necessary preparations.
  Ten yuan is enough.