题目

                            The case for college has been accepted without question for more than a generation．     All high school graduates ought to go, says conventional wisdom and statistical evidence, because college will help them earn more money, become “better” people, and learn to be more responsible citizens than those who don’t go．     But college has never been able to work its magic for everyone．And now that close to half our high school graduates are attending, those who don’t fit the pattern are becoming more numerous, and more obvi哺乳动物长时间未饮水导致机体脱水时，会发生的生理现象是（ ） A. 血浆渗透压降低B. 抗利尿激素增加C. 下丘脑渗透压感受器受到的刺激减弱D. 肾小管和集合管对水的重吸收作用减弱