Student participation（参与）in the classroom is not only accepted but also expected of the student in many courses.Some professors base part of the final grade on the student′s oral participation.Although there are formal lectures during which the student has a passive role（i.e.,listening and taking notes）,many courses are organized around classroom discussions,student questions,and informal lectures.In graduate discussions the professor has a"manager"role and the students make presentations and lead discussions.,The students do the actual teaching in these discussions.

A professor′s teaching method is another factor（因素）that determines the degree and type of student participation.Some professors prefer to control discussion while others prefer to guide the class without controlling it.Many professors encourage students to question their ideas.Students who object to the professor′s point of view should be prepared to prove their positions.

In the teaching of science and mathematics,the controlling mode of instruction is generally traditional,with teachers presenting formal lectures and student staking notes.However,new educational trends have turned up in the humanities and social sciences in the past twenty years.Students in education,society,and history classes,for example,are often required to solve problems in groups,design projects,make presentations,and examine case studies.Since some college or university courses are"practical"rather than theoretical,they pay more attention to"doing"for themselves.

The reason why some professors ask students to make presentations and lead discussions is that__________

• A.these professors are often not well prepared before class
• B.these professors want to stress"doing"
• C.these professors want to test the students'abilities
• D.these professors are not willing to teach theory