Normally a student must attend a certain number of courses in order to graduate, and each course which he attends gives him a credit which will be counted towards a degree. In many American universities the total work for a degree consists of thirty-six courses, each lasting for one term. A typical course consists of three classes per week for fifteen weeks; a student will probably attend four or five courses during each term while attending a university. Normally a student may expect to take four years attending two semesters each year. Of course, they can work for the degree over a longer period. It is also possible for a student to move between one university and another during his degree course, though this is not in fact done as a regular practice.
Every course that the student takes will be given a grade, which is recorded and available for the student to show to their prospective employers. All this imposes a constant pressure and strain of work on students. But some students still spare their time to take part in the student affairs. Elections to positions in student organizations arouse much enthusiasm. The effective work of maintaining discipline is usually performed by students who advise the academic authorities. Any student who is thought to have broken the rules, for example, by cheating, has to appear before a student court. With the large numbers of students, the operation of the system does include a certain number of activities. A student who has held one of these positions of authority is much respected and it will be helpful to him later in his career.
American university students are usually under pressure of work because__________

A.their academicperformance will affect their future careers

B.they are heavily involvedin student affairs

C.they have to observe university discipline

D.they want to run for position of authority