John ( ) be in the classroom because I saw him in the library just now.A.mustn't B.isn't able to C.can't D.may not
问题描述：
John ( ) be in the classroom because I saw him in the library just now.
A.mustn't B.isn't able to C.can't D.may not
答
其实4个答案从语法，还有意思上来讲都是可以的，
不过正常人说话是用cannot 或者 can't
就是跟语感有关系的。
答
正确：C
must be一定（肯定推测）； can't be 不可能（否定推测）
答
C.can't 表示非常绝对的判断.
因为前面所说,可以推断.