You should try to make your vocabulary --.A:many B:more C:mu

igger,词汇容量用大小形容,不用多少形容.
就如水池的容量用大小形容,不用多少形容是一个道理.
为了使我的答案有说服力,参见以下文段：
【The words you know are called your vocabulary.You should try to make your vocabulary bigger.Read as many books as you can.There are plenty of books written in easy language.Your dictionary is your most useful book.】
真的真的真的希望帮助到你!