问题补充：
The number of students in our school about 30,000 and them study hard.
A. is; a large amount of
B. are; large amount of
C. are; a number of
D. is；a large number of
答案：
A. is; a large amount of
B. are; large amount of
C. are; a number of
(答案→)D. is；a large number of
解析：短语辨析及主谓一致. a large amount of大量,修饰不可数名词; a number of 大量,许多的,修饰可数名词复数.句意:我们学校的学生的数目大约是30000人,并且他们中大部分学习很努力.前文主语number表示抽象含义,不可数,故谓语动词用单数.下文them表示复数含义,故选D.
