设函数z=x2+y2，则全微分dz=______。

临床上脊麻应用率逐渐下降的主要原因是（）

A.脊麻后腰背痛

B.脊麻后尿潴留

C.脊麻后颅内感染

D.脊麻后头痛

E.害怕注入错误药

胸痹之心血瘀阻证的临床主要特征是( )

A．胸部刺痛，固定不移，入夜尤甚
B．胸痛如窒，痛引肩背，痰多，肢体沉重
C．胸闷隐痛，时作时止，心悸气短
D．胸痛如绞，感寒尤甚，时作时止，胸闷气短
E．以上均不是

“不论富贵，不论权贵和庄稼人都应一视同仁，并不因特殊情况而有出入。”英国哲学家洛克的这一名言的积极意义在于，公民参与政治生活必须（）。

A.坚持权利与义务相统一的原则

B.遵循法律面前一律平等的原则

C.坚持个人、集体和国家利益相结合的原则

D.坚持经济平等和政治平等相一致的原则

That rapscallion who leaps off the monkey bars, landing smack onto an innocent 3-year-old bystander, and skips off, giggling all the while According to a new paper out of Israel, he may not feel all that bad about the incident. The study, conducted by Dr. In bal Kivenson Bar-On at the University of Haifa, shows that high levels of fearlessness in 3-and 4-year-olds is ply associated with aggression and a lack of sympathy. This news will likely surprise risk-loving America, where parents typically beam with pride when their undaunted child mounts the big slide.

Fearlessness is a far-end point on the spectrum of what psychologists call the "approach and withdrawal dimension"—people’s tendency to approach new stimuli (to gain information and acquire new skills ) and withdraw from unfamiliar stimuli (to avoid danger). Striking the right balance is considered crucial to man’s survival. But what about preschoolers’ There’s a clear downside, Dr. Kivenson Bar-On discovered, after she observed lots of preschool play and machinations. In total, she documented 80 children at preschool, home and in the lab, measuring their propensity for fearlessness and other social and emotional characteristics at the beginning and end of one year. Fearlessness was measured by observing reactions to various fright-inducing situations: separation from parents, the roar of a vacuum cleaner, a jack-in-the-box and the like. Those who displayed greater levels of fearlessness, the study found, had no trouble recognizing facial expressions of anger, surprise, happiness and sadness in other children—but they had a hard time identifying fear.

Over all, they were "emotionally shallow" and showed lower levels of sympathy. They took advantage of friends and lacked regret over inappropriate conduct. "These findings," the paper explains, " suggest that fearlessness in preschool constitutes a clear risk factor for developmental pathways that lead to problems in morality, conscience development, and severe antisocial behaviors. " At the same time, fearless children tended to be highly sociable. "One of the most interesting findings was that we could discriminate between friendliness and sympathy," Dr. Kivenson Bar-On said. "These kids are curious, easygoing and friendly, but they have a hard time recognizing emotional distress in others. "

Jamie Ostrov, a psychology professor at the State University at Buffalo who studies aggression, says that children at the extreme end of the fearless spectrurn "may be charming, but they’re also highly manipulative and deceptive and skilled at getting their way—even at age 3 or 4. " It could be that fearless children need per distress cues to active their autonomic nervous systems, limiting their ability to detect distress cues in others. It seems to be, if I’m not worried about this, you can’t be, either. But should we be

According to the second paragraph, we may know（）

A. fearless children are easy to live

B. fearless children’s character downside

C. fearless children are not sensitive to fear

D. fear children are hard to distinguish different kinds of look

急性腹膜炎最主要的临床表现是（）

A.腹痛

B.恶心、呕吐

C.发热

D.血压下降

E.全身中毒症状