问题详情

Many instructors believe that an informal, relaxed classroom environment is【1】to learning and innovation.
It is not uncommon for students to have【2】and friendly relationships with their professors.
The【3】professor is not necessarily a poor one and is still【4】by students. Although students may be in a(n)【5】position, some professors treat them as【6】.However, no matter how【7】professors would like to be, they still are in a position of【8】.
Professors may【9】social relationships with students outside the classroom, but in the classroom they【10】the instructor"s role. A professor may have coffee one day with students【11】the next day expect them to【12】a deadline for the【13】of a paper or to be. Prepared【14】a discussion or an exam. The professor may give【15】attention outside of class to a student in【16】of help but probably will not treat him or her differently when it【17】evaluating school work. Professors have several roles【18】students; they may be counselors and friends as well as teachers. Students must【19】that when a teacher"s role changes, they must appropriately【20】their behavior. and attitudes.
(1)
A．instructive
B．conducive
C．constructive
D．healthy请帮忙给出正确答案和分析，谢谢！