单选题 Many IQ tests show that there are no significant differences in the mean, or average scores of IQ tests between men and women. When a new IQ test, is being constructed, it is quite easy to find test (51) that are not answered correctly (52) the same proportions of men and women, (53) these are usually then eliminated from the test. So, to some (54) the fact that no differences are to be found in our current IQ tests between the (55) for the two sexes is hardly surprising.
There are, (56) , differences in the standard deviations(偏差)or variability of the (57) of the two sexes in many IQ tests, (58) men showing the greater variation. The (59) of many IQ test scores are such (60) they approximate to the normal curve(正规曲线). If we regard some arbitrary lower score on a test as a classification like "educational subnormal(智力上逊常的人)" (ESN) and some equally arbitrary (61) score as "gifted", we then find that there is higher ratio of ESN males to women and likewise we (62) that there are more gifted men than women, even though the average scores are the same.
The (63) of men and women are known to differ somewhat in size, with women having about 200g less tissue (64) the other hand, they also tend to (65) less body mass, and over the phylogenetic(系统发育的)scale, the best index of species intelligence is the ratio of body mass to brain size.