—Class is over.—Look, number of students are playing football there. Let’s go and join t

—Class is over.
—Look, number of students are playing football there. Let’s go and join them.
A. /
B. a
C. an
D. the

A. /(答案→)B. aC. anD. the解析：句意：--下课了。--看，有许多的学生正在那踢足球。让我们去加入他们吧。a number of是大量的，等于a lot of后面接名词复数。the number of是……的数量，后面接名词复数，例如:A number of apples are red许多苹果是红色的。The number of students is 2000学生的数量是2000人。a number of…… 许多……或者很多……,谓语动词要用复数e.g. A number of students are playing.很多学生在玩。the number of……的数量 谓语动词要用单数e.g. The number of the students is 50.学生的数量是50。故选B

哦，回答的不错