问题补充：
There are students in my school. students in my school is over 5000.
A. a number of, A number of
B. the number of, The number of
C. the number of, A number of
D. a number of, The number of,
答案：
A. a number of, A number of
B. the number of, The number of
C. the number of, A number of
(答案→)D. a number of, The number of,
解析：a number of 表示大量的，后接可数名词复数形式，作为主语时，相当于复数形式，而the number of 表示···的数量，作为主语时相当于三单形式，故选D
