In the second paragraph the author uses an analogy (类比) that assumes that general principles are similar to______.

A．superficial reading is valueless
B．a successful scientist usually confines his reading to the problem under investigation
C．a research worker cannot benefit from superficial and "skim" reading over a wide field if he doesn't have a background of knowledge
D．if a research worker has wide interests, he is sure to succeed in his own specialty

A．has wide interests and reads original books or articles
B．is a person with originality, which comes from his diverse knowledge
C．not only reads widely but also cultivates diverse interests
D．benefits more from teaching than from his research