Although blind rage of human being is perhaps the result of survival instinct, strangely enough, we seldom take it out on ______.

A．He’s trying to buy a used car.
B．He’s trying to pass a driving test.
C．He’s trying to have his car repaired.
D．He’s trying to sell a car.

A．Importance of knowledge.
B．Differences between knowledge and practice.
C．How to gain experience.
D．Book knowledge and practical experience.