问题补充：
—Quite a lot of students failed in the math exam．
—Exactly．It is their abilities．
A. within
B. over
C. against
D. beyond
答案：
A. within
B. over
C. against
(答案→)D. beyond
解析：介词辨析。 A．在……之内 B．越过；在……之上 C．靠；反对D．超出；句意：相当多的学生在数学考试中不及格。——确实的。有点超出他们的能力了。故选D。
