Many people realized that ( ) good knowledge of English was ( ) must in international trade today.

题目

Many people realized that ( ) good knowledge of English was ( ) must in international trade today.
A./,the
B.a,a
C.a/the
D.the,the
为什么选B,

答案

B,a knowledge of..固定搭配,一门.的知识..is a must,固定搭配,.是一种必要
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