病例对照研究的缺点是( )A.需要样本量大B.研究所需时间长C.易产生医德问题D.

题型:单项选择题

问题:

病例对照研究的缺点是( )

A.需要样本量大
B.研究所需时间长
C.易产生医德问题
D.回忆时易发生偏倚
E.不能估计相对危险度

考点:公卫执业医师公卫执业医师
题型:单项选择题

阅读短文,按要求完成后面的任务。

     Why does the Leaning Tower of Pisa in Italy lean? It leans because of a mistake. It has leaned almost

 since the day the tower was built. (1) In 1174, the people of Pisa, Italy wanted to build a bell tower.

 They wanted the tower to be the most beautiful bell tower in Italy. The city also needed a bell tower

 because the church did not have one.

     As soon as the first floor of the building was finished, the tower started to lean. Builders tried to make

  the building straight by adding more floors, but the Leaning Tower only got worse as the tower grew

 180,years, it, took, to, almost, the, tower, finish (2) Like all old buildings, it is also falling apart.  If

 someone cannot figure out a way to save the tower, the Leaning Tower of Pisa will fall down in less than

 200 years.

1. 请将( 1) 处划线句子翻译成汉语。

     ____________________________________________________

2. Why did the people of Pisa build the Leaning Tower?

     __________________________________________________________

3. What action did the builder take to make the tower straight?

      __________________________________________________________

4. 请将( 2) 处划线部分排列成一个通顺的句子。

     _______________________________________________________

5. What's the Chinese meaning of "figure out"?

   ____________________________________________________________

题型:单项选择题
如图所示,一光滑的圆锥内壁上,一个小球在水平面内做匀速圆周运动,如果要让小球的运动轨迹离锥顶远些,则下列各物理量中,不会引起变化的是()

A.小球运动的线速度

B.小球运动的角速度

C.小球的向心加速度

D.小球运动的周期

题型:单项选择题

2008年10月12日至17日,商务部将在深圳举行中国国际高新技术成果交易会,签订高新技术项目。这些项目

A.是特殊商品,能创造出比劳动力价值更大的价值

B.是生产要素,但不是商品,只有使用价值,没有价值

C.是商品,但只有在交易成功的条件下才成为商品

D.是生产要素,也是商品,既有使用价值,又有价值

题型:单项选择题

已知下列反应均为放热反应,其中反应热最小的是

A.2A ( l ) + B (l ) =" 2C" (g )△H1

B.2A ( g ) + B ( g ) =" 2C" (g )△H2

C.2A ( g ) + B ( g ) =" 2C" ( l )△H3

D.2A ( l ) + B ( l ) =" 2C" ( l )△H4

题型:单项选择题

溶血性黄疸的特点是()

A.血中结合胆红素含量增高

B.血中胆素原剧减

C.尿中胆红素增加

D.未结合胆红素浓度增高

E.粪便颜色变浅

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