Twenty years is not a long time.
Ten dollars is too dear.
My family is big one.
My family are watching TV.
(3)不定代词由all, most, more, some, any, none作主语时，也要依这些代词暗示的意义来抉择谓语动词的单复数形式。假如代词代表复数可数名词，谓语动词用复数;假如代词代表单数可数名词或不行数名词，谓语动词用单数。譬喻：
All of the work has been finished.
All of the people have gone.
Who is your brother?
Who are League members?
It is said that 35 per cent of the doctors are women.
Three -fourths of the surface of the earth is sea.
(6)half, the rest等暗示不定命量的名词作主语时，假如所指为复数意义，动词用复数;假如所指为单数意义，动词用单数。譬喻：
I have read a large part of the book, the rest is more difficult.
Only ten students attended the class because all the rest were off sick.
What she said is correct.
What she left me are a few old books.
The sick have been cured and the lost have been found.
The dead is a famous person.