Children in school areinto different levels of grades according to how much they know.A. c

问题补充：

Children in school areinto different levels of grades，according to how much they know.

A. combined

B. classified

C. listed

D. clarified

答案：

A. combined

(答案→)B. classified

C. listed

D. clarified

解析：句意：根据孩子们知道的多少，他们在学校被分为不同层次的年级。classify意思为“将……分类，分班”；其他几个词没有这层意思，不合题意。combine结合；list列举，列出；clarify澄清，阐明。