A large number of students planting trees now the number of the students 2000.A. is isB.

问题补充：

A large number of students planting trees now, the number of the students 2000.

A. is, is

B. are, is

C. is, are

D. are, are

答案：

A. is, is

(答案→)B. are, is

C. is, are

D. are, are

解析：考察主谓一致。句意：许多学生正在植树。这些学生的数目是2000.结合语境可知前文a number of表示许多人，主语是复数，故系动词用are。下文the number of……的数目，主语是抽象名词，不可数，故系动词用is。选B。