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