阅读短文，选择正确答案。

 Students learn their lessons in class. In class teachers teach them. Student sit in the classroom listening to the teacher. This is a way of learning. Is this the only way for students to learn something? Of course not. There is another way to learn. That is, students can teach themselves. For example, if you cannot remember something when you are doing your homework, you can look at your book to find the answer. This is a way to teach yourself. And it is not a difficult thing. We can do this at any place and at any time.