单选题设函数在在(-∞，+∞)上可导，则有______。A．a=0，b=2B．a=0，b=1C．，b=2D．a=e-1，b=1

单选题______．

单选题3阶矩阵且r(A*)=1，则有()

单选题已知复数z，若|z|=1，则复数是______。A．实数B．虚数但不一定是纯虚数C．纯虚数D．实数虚数不确定

单选题设两个随机变量X与Y相互独立且同分布：下列各式中成立的是______．

单选题设φ(x)是x到离x最近的整数的距离，求。

单选题为处理含有某种杂质的污水，要制造一个底宽为2m的无盖长方体沉淀箱(如图所示)，污水从A孔流入，经沉淀后从B孔流出，设箱体的长度为am，高度为bm，已知流出的水中该杂质的质量分数与a、b的乘积ab成反比，现有制箱材料60m2，问当a、b各为______m时，经沉淀后流出的水中该杂质的质量分数最小(A、B孔的面积忽略不计)。

单选题根据市场调查结果，预测某种家用商品从年初开始的n个月内累积的需求量Sn(万件)近似地满足(n=1，2，…，12)。按此预测，在本年度内，需求量超过1.5万件的月份是______。A．5月、6月B．6月、7月C．7月、8月D．8月、9月

单选题______．

单选题The mid-sixties saw the start of a project that, along with other similar research, was to teach us a great deal about the chimpanzee mind. This was Project Washoe, conceived by Trixie and Allen Gardner. They purchased an infant chimpanzee and began to teach her the signs of ASL, the American Sign Language used by the deaf. Twenty years earlier another husband and wife team, Richard and Cathy Hayes, had tried, with an almost total lack of success, to teach a young chimp, Vikki, to talk. The Hayes*s undertaking taught us a lot about the chimpanzee mind, but Vikki, although she did well in IQ tests, and was clearly an intelligent youngster, could not learn human speech. The Gardners, however, achieved spectacular success with their pupil, Washoe. Not only did she learn signs easily, but she quickly began to string them together in meaningful ways. It was clear that each sign evoked, in her mind, a mental image of the object it represented. If, for example, she was asked, in sign language, to fetch an apple, she would go and locate an apple that was out of sight in another room. Other chimps entered the project, some starting their lives in deaf signing families before joining Washoe. And finally Washoe adopted an infant, Loulis. He came from a lab where no thought of teaching signs had ever penetrated. When he was with Washoe he was given no lessons in language acquisition—not by humans, anyway. Yet by the time he was eight years old he had made fifty-eight signs in their correct contexts. How did he learn them? Mostly, it seems, by imitating the behavior of Washoe and the other three signing chimps, Dar, Moja and Tam. Sometimes, though, he received tuition from Washoe herself. One day, for example, she began to swagger about bipedally, hair bristling, signing food! food! food! in great excitement. She had seen a human approaching with a bar of chocolate. Loulis, only eighteen months old, watched passively. Suddenly Washoe stopped her swaggering, went over to him, took his hand, and moulded the sign for food (fingers pointing towards mouth). Another time, in a similar context,, she made the sign for chewing gum—but with her hand on his body. On a third occasion Washoe picked up a small chair, took it over to Loulis, set it down in front of him, and very distinctly made the chair sign three times, watching him closely as she did so. The two food signs became incorporated into Loulis's vocabulary but the sign for chair did not. Obviously the priorities of a young chimp are similar to those of a human child! Chimpanzees who have been taught a language can combine signs creatively in order to describe objects for which they have no symbol. Washoe, for example, puzzled her caretakers by asking, repeatedly, for a rock berry. Eventually it transpired that she was referring to brazil nuts which she had encountered for the first time a while before. Another language-trained chimp described a cucumber as a green banana. They can even invent signs. Lucy, as she got older, had to be put on a leash for her outings. One day, eager to set off but having no sign for leash, she signaled her wishes by holding a crooked index finger to the ring on her collar. This sign became part of her vocabulary.