下列关于气控液压换向阀的说法（）。 A.气控液压换向阀是气控液压系统中的气、液转换元

Visitors to this country are normally admitted for six months, but foreign students can usually stay for one year. They must (52) an educational institution, and they are required to study for a minimum of fifteen hours a week on a (53) course. Prospective students have to show that they can afford their studies, and that they have sufficient (54) resources to support themselves (55) in this country.

In order to work here the foreigner needs a work permit, (56) must be applied for by his prospective employer. The problem here is that the Department of Employment has the right to grant or (57) these permits, and there is little that can be done (58) it; it would be extremely unwise for a foreign visitor to work (59) a permit, since anyone doing so is liable to immediate deportation (驱逐出境). There are some people from the Common Market countries, who are often given (60) residence permits of up to five years. Some other people, such as doctors, foreign journalists, authors and others can work without permits, and foreign students are normally allowed to (61) part-time jobs while they are studying here.

55().

A.after 

B.but 

C.while 

D.before

( )1938年提出了公司(股票)价值评估的股利贴现模型(DDM)，为定量分析虚拟资本、资产和公司价值奠定了理论基础，也为证券投资的基本分析提供了强有力的理论根据。

A．凯恩斯
B．艾略特
C．希克斯
D．威廉姆斯

属于糖尿病微血管病变的是

A．冠心病

B．下肢坏疽

C．肾动脉狭窄

D．脑血管意外

E．糖尿病肾病

患者，男，38岁。左侧腰胀痛2年，局部皮肤无红肿等表现，左侧肋脊角叩击痛阳性，当地医院检查发现左肾占位性病变，发病以来无血尿及膀胱刺激症状。

若占位性病变为肾癌所致，下列哪项对诊断最有帮助（）

A.放射性核素肾图

B.腰痛

C.腰腹部肿块

D.静脉肾盂造影

E.肾动脉造影

F.B超

1992年巴塞罗那奥运会上，在唯一一项男女同场竞技的项目——双向飞碟比赛中，中国女运动员（）战胜所有男运动员，获得金牌。

A、吴晓旋

B、杜丽

C、张山