问题补充：
the teachers should try to keep the students in their class(interet)
可以是interets吗?没有be动词啊,be intereted in?
一种理解方法:keep sb.sth.done .
另一种从句子结构,语法角度:
the teachers should try to keep the students
主谓宾都有了.
后面的成分就是补语状语之类.
keep the students 意思不完整,要有补充的成分.(intereted) in their class 在他们的课堂上保持感兴趣的状态.这里要用的是形容词性的.
所以,interets这种名词,是不行的.
the teachers should try to keep the students (intereted) in their class(interet)