有些指示词可以作单数也可以作复数：

　　All the city is clean and very beautiful.但：All the cities are clean and beautiful.

　　Anything good is good to him.但：Any streets in this city are familiar to him.

　　Someone(or Somebody) has come.但：Some friends have come.

　　Such a person is never happy.但：Such persons are always dissatisfied.

　　A certain boy has broken it.但：Certain boys have done it.

　　Another girl loves him.但：Other girls love him.

　　Each wears a cap.但：They each wear caps.

　　Either(or Neither)(作形容词)party is right.

　　Either(or Neither)(作代词)of the two parties has its good leader.

　　Either(or Neither)(作代词) have their good leaders.(口语体)

　　Neither Jan，nor Helen，(nor) Belinda，nor Dorotby have come home.(口语体)

　　What，who，which可作单数也可作复数：

　　Who are(or is) waiting outside?

　　Which are(or is) yours?

　　What引起的从句多作单数：

　　What he is doing is trivial.

　　What made me sad was his unhappy marriage.

　　如果补语是一个复数名词，what引起的从句也可作复数看待：

　　What children like are stories.

　　What seem to be boats are rocks.

　　这主要得根据情况决定，试比较下面句子：

　　What(= A thing that) seems to be a rat is something else.

　　What(= Things that) seem to be rats are some other ani-mals.

　　His family(作为整体)is large.

　　集体名词可以表示一个集体，可以看作是单数，如果表示其成员，就可以作复数看待，特别是在英国：

　　His family(= The members of his family) are all well.

　　一个集体名词若有every，each，a，this，that修饰，常常作单数看待：

　　Every family in this area is equipped with guns.

　　This club is devoted to the study of photography.

　　A committee is appointed to inquire into the matter.

　　The committee are at dinner.

　　The cavalry was repulsed.

　　The cavalry wear scarlet trousers.

　　This team is well organized.

　　Our(而不是 These)team are good players.

　　The company was organized by Mr.Johnson and they are mostly Americans.

　　The mob becomes more and more violent.

　　The mob were throwing up their caps and cheering.

　　This hotel is by the seaside.

　　All the hotel are startled at the alarm.

　　This class is a small one.

　　Our class are quarrelling among themselves.

　　The old couple(or pair)is happy.

　　The young couple(or pair) are quarrelling with each other.

　　但：This twin(one of the twins)is like the other.

　　These twins are like each other.

　　The litter of pups was born yesterday.(动物的集体)

　　The litter of pups were playing with each other.

　　Every herd of elephants in this area seems to be happy and free.

　　The flock of birds were flying about.