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问题 单项选择题

铣一圆柱矩形螺旋槽凸轮，当导程是Pz时，外圆柱表面的螺旋角为30°，则螺旋槽槽底所在圆柱表面的螺旋角为（）。

A、0° 

B、<30°

C、>30° 

D、30°

答案

参考答案：B

多项选择题 案例分析题

病历摘要：患者女性，23岁，学生。进行性四肢瘫痪半个月而于2月26日入院。患者于2月1日劳动后腹部绞痛，无呕吐及腹泻。外科诊断为肠梗阻，行剖腹探查术，术中见轻度大网膜与横结肠和小肠粘连，行分离术，术后恢复良好。11日出现骶部疼痛，麻木，并扩展至下肢、腹部及颈部。15日觉双下肢无力，口周麻木，呼吸、排尿费力，小便淋漓不尽，四肢无力逐渐加重，活动困难而入院。病前无发热、腹泻。既往有类似腹痛史，曾在外院诊断为胰腺炎。体查：呼吸稍困难，28次/分。心率120次/分，血压、体温正常。神经系统检查发现水平眼震，双额纹浅，闭眼、示齿、鼓腮力弱。C3以下痛触觉减退，以C3-4，T11-12，S1以下明显。四肢近端肌力0级，远端肌力2级，肌张力低，四肢腱反射消失，病理征（-）。腰穿压力105mmH2O，脑脊液常规正常，蛋白0.52g/L。

经化验尿卟胆原（+）、尿卟啉（+），确诊为血卟啉病。血卟啉病可能有以下表现（）

A.精神症状

B.癫痫

C.偏瘫、震颤

D.间隙性腹痛

E.呼吸困难

F.周围神经病变

G.感光性皮炎

H.尿色深红
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单项选择题

According to the United States government, people are classified as homeless if they have no place to stay and no expectation of finding a place for the next thirty days, Although technically accurate, that is an impersonal assessment of an enormous and very human problem,
The homeless population represents all of us Americans, It includes men and women, the elderly, children, and infants. Its members are from all ethnic (种族的) groups. What they have in common is poverty.
Currently in the U.S., thirty-nine million people live in poverty. When money is really tight, paying the rent or buying food often becomes a choice. Government assistance in the form of food stamps does help but, as one homeless man explains, you can’t pay the rent with food stamps.
With no money for rent, the streets and homeless shelters become the alternative.

The breakup of families is likely to lead to homelessness because a parent with kids may ______.
A. lose his or her job in today’s economy B. be unable to look after the kids
C. not have enough incomeD. find residence at a homeless shelter

Although men constitute the largest group within the homeless population, homeless women with children are rapidly joining them. In fact, one quarter of the homeless people in the U.S. are teenagers and young children.
People may become homeless for numerous reasons. However there are certain factors that many of these individuals have in common. They include a lack of adequate education and job skills. A majority of the teenagers and adults have not completed high school.
The abuse of alcohol and drugs is also a common factor. One third of the adult homeless population abuses alcohol, while one quarter of the same group uses drugs.
Some members of this population suffer mental health problems. Within the past several years many institutions for the menially ill have been closed and their patients sent "home". Unfortunately, a number of those people have no home to go to and they are unable to adequately look after themselves.
Job loss in today’s economy has also become a real factor in the loss of people’s homes. The breakup of families through abandonment and divorce are also contributing factors, particularly when there are children involved. The parent who is left to care for the kids with inadequate income may be forced to depend on the homeless shelters to put a roof over their heads.
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