People have wondered for a long time how their personalities and behaviors are formed. It is not easy to explain why one person is intelligent and another is not,or why one is (62) and another ’is competitive.
Social scientists are, of course, extremely interested in these types of questions. They want to explain why we possess certain characteristics and (63) certain behaviors. There are no clear answers yet, but two (64) schools of thought on the matter have (65) . As one might expect, the two (66) are very different from one another, and there is a great deal of (67) between proponents (支持者) of each theory. The controversy is often (68) to as "nature vs nurture".
Those who support the "nature" side of the conflict believe that our personalities and behavior patterns are (69) determined by biological and (70) factors. That our environment has (71) , if anything, to do with our abilities, characteristics and behavior is central to this theory. Taken to an extreme, this theory maintains that our behavior is predetermined (72) such a great degree that we are almost completely (73) by our instincts.
Proponents of the "nurture" theory, or, (74) they are often called, behaviorists, claim that our environment is more important than our biologically based instincts in determining (75) we will act. A behaviorist, B. F. Skinner, sees humans as beings whose behavior is almost completely (76) by their surroundings. The behaviorists’ view of the human being is quite (77) ; they maintain that, like machines, humans (78) to environmental stimuli as the (79) of their behavior.
Neither of these theories can yet (80) explain human behavior. In fact, it is quite likely that the (81) to our behavior lies somewhere between these two extremes. That the controversy will continue for a long time is certain.

A．respond

B．attribute

C．object

D．tumble