问题
选择题
The ability _________ an idea is as important as the idea itself.
A．expressing
B．expressed
C．to express
D．to be expressed
答案
C
本题考查非谓语动词作定语的用法。express 修饰的是ability, 为主动关系，所以答案锁定在A，C之间；ability作为一个抽象名词，通常使用动词不定式做定语；当然我们还可以联系短语be able to do sth，不难推断正确选项为C