The number of students in our school 4000 and a number of themgood at playing ping pong.A.

问题补充：

The number of students in our school 4000 and a number of themgood at playing ping pong.

A. is, is

B. are, are

C. is, are

D. are, is

答案：

A. is, is

B. are, are

(答案→)C. is, are

D. are, is

解析：我们学校学生的数目是4000，他们中许多人擅长打乒乓球。结合语境可知前文number表示数字，故be动词用单数。下文a number of them表达复数含义，故系动词用复数。选C。