In the United States, teaching is very important. If teachers do not teach well, students

In the United States, teaching is very important. If teachers do not teach well, students plain. If many students do not understand, people think that the teacher does not do a good job. The teacher has big responsibility to make sure students understand. In a sense, students are consumers and the teacher is offering services.
Students have the right to evaluate their teachers, and they usually do so at the end of each course. That evaluation includes lots of aspects of teaching, such as explanation, preparation, using good examples, answering questions, and organization of classes.
Students are supposed to read required textbooks and remended books before classes. Without reading them, they will find it very difficult to understand the class. Basic courses on doing research and writing papers are taught at the beginning of the program. They teach things very concretely(具体地) and clearly. Students are expected to apply what they have learned to their studies.
Classes are usually divided into lectures and seminars. There are some lecture classes, where the teacher just gives a lecture, and students ask questions at the end. Most graduate level classes are lectures and discussions. Participating in discussions is very important. Higher level classes involve very little lecturing. They emphasize discussion and presentation by the students.
1According to the passage, good teachers should     .
A．try to please their students
B．treat their students as consumers
C．understand their students well
D．made sure their students understand
2What are students expected to do before attending a class?
A．Go over the lessons thoroughly.
B．Understand the textbooks well.
C．Do the reading assignments.
D．Prepare on outline for discussion.
3When a program starts, students should first     .
A．learn how to do research and write papers.
B．have some learning experience
C．learn about the course concretely and clearly
D．know how to participate in discussions.
4Higher level classes are taught mainly through     
A．giving a lot of lectures to students
B．involving students in discussions
C．asking students questions in class
D．answering students’ questions in classD