Few scientific fields are as full of risk as that of research into human intelligence. The two questions that (1) over and over again are "is it a result of nature or nurture" and "does race make a difference"
Making (2) comments about the second question can be a (3) move, as James Watson, a co-discoverer of DNA structure, recently found. He suggested that he was " (4) about the prospect of Africa" (5) "all our social policies are based on the fact that their intelligence is the same as ours (white people) (6) all the testing says not really". Such (7) by Dr. Watson are not merely (8) , they are scientifically weird. If the term (9) has any useful scientific meaning, then Africa, the continent where modern humanity began, is most racially diverse. The resulting (10) among the public forced Dr. Watson to leave his laboratory.
(11) , the study of the first question (12) between intelligence and genetics— has some wiser practitioners. One of them, Terrie Moffitt, of King’s College, has just (13) a project judging the relative importance of nature and nurture. Dr. Moffitt’s team (14) the effect on intelligence of breastfeeding, but in a genetic context. Previous studies have shown that breastfed children are more intelligent, (15) about six IQ points, than those given baby formulas.
The team, however, (16) the involvement of a gene called FADS2, which comes in two varieties, known as C and G. The researchers (17) if these two varieties interacted differently with breast milk. (18) on data from two groups of people, they found that the intelligence increase associated with breastfeeding only happened to people having (19) at least one copy of the C variety. The effect did not. (20) on the social classes or IQs of the parents.
6（）
A.however
B.whereas
C.since
D.as
参考答案：B
解析：
[试题考点] 上下文逻辑关系和连词用法辨析。
[解题思路] 本题空格前的内容意为“所有的社会政策都是基于非洲人与白人智力相同的事实而制定的”，空格后的内容意为“所有的实验结果表明情况并非如此”，很显然，空格前后形成转折关系，四个选项中表示转折关系的有选项[A]和选项[B]，但选项[A]however在句中连接两个分句表示转折时，其前后要用逗号。选项[B]whereas引导对比分句，意为“然而；但是”，相当于while，放在此处用来对比事实情况和实验结果完全不同，含有强烈的转折意味，故选项[B]正确。
[干扰排除] 选项[C]since用作连词连接两个分句时，意为“由于，既然；自从”，既可表因果，也可表时间，选项[D]as意为“由于；随着”，表原因或伴随，很显然这两项与空格前后的逻辑关系不符，故排除。