Many people agree that________knowledge of English is________must in international trade today.A.a；a B.the；an C.the；the D.不填；theWHY?

Many people agree that________knowledge of English is________must in international trade today.A.a；a B.the；an C.the；the D.不填；theWHY?
Many people agree that________knowledge of English is________must in international trade today.
A.a；a B.the；an C.the；the D.不填；the
WHY?

Many people agree that________knowledge of English is________must in international trade today.A.a；a B.the；an C.the；the D.不填；theWHY?
选A
the reason
对于knowledge是一个非指定性质的名词,按照习惯,用great knowledge of
或者 a knowledge of表示某方面的一些知识.
第二个must,是必须掌握的一样东西,所以可作为可数名词,使用a
其实,这个搭配可作为习惯将其记住的.没有太多的道理.