Many people agree that （ ）knowledge of EnglishMany people agree that （ ）knowledge of English is a must in（ ）international trade.A.a,/ B.the,an C.the,the D./,the 为什么?

Many people agree that （ ）knowledge of EnglishMany people agree that （ ）knowledge of English is a must in（ ）international trade.A.a,/ B.the,an C.the,the D./,the 为什么?
Many people agree that （ ）knowledge of English
Many people agree that （ ）knowledge of English is a must in（ ）international trade.A.a,/ B.the,an C.the,the D./,the 为什么?

Many people agree that （ ）knowledge of EnglishMany people agree that （ ）knowledge of English is a must in（ ）international trade.A.a,/ B.the,an C.the,the D./,the 为什么?
第一空：a knowledge 指对英语的了解,此处抽象名词表示种类,前面应加不定冠词.a knowledge of 指的是比较广泛的某门学科的综合知识.而the knowledge of指的是比较具体的某种办法的知识,比如The Knowledge of Life（生活小常识）,The Knowledge of Healing（疗愈的知识）.英语知识应该是一个综合的知识,它可以包括英语会话和英语社交常识等等,所以用a.
第二空：international trade指国际贸易,表泛指,故不加冠词