问题 单项选择题

特异危险度是指

A.暴露组的发病率或死亡率与未暴露组的发病率或死亡率之比

B.暴露组的发病率或死亡率与未暴露组的发病率或死亡率之差

C.暴露组的发病率或死亡率与未暴露组的发病率或死亡率之积

D.暴露组的发病率或死亡率与未暴露组的发病率或死亡率之和

E.暴露组的发病率或死亡率与未暴露组的发病率或死亡率的平方和

答案

参考答案:B

解析:特异危险度,又叫归因危险度、率差,是指暴露组的发病率或死亡率与未暴露组的发病率或死亡率之差,反映发病或死亡危险特异地归因于暴露因素的程度。此题备选答案中的干扰项是A——暴露组的发病率或死亡率与未暴露组的发病率或死亡率之比,即相对危险度。二者密切相关,但它们的意义却不同。相对危险度说明暴露对于个体比未暴露情况下增加相应疾病的危险是多少倍;特异危险度则是对于人群来讲,暴露比未暴露情况下增加超额疾病的数量,如果暴露因素消除,就可以减少这个数量的疾病发生。前者具有病因学的意义,后者更具有疾病预防和公共卫生学上的意义。

阅读理解

阅读理解

     ''Mom, can I bake some bread?" We were 15; my best friend, Hanna, and I, determined to try our

hands at creating some beautiful bread.

     "It's not worth the trouble," my mother said. "It takes lots of time and makes a big mess. Our bakery

bread is delicious without all that effort."

     Begging was useless. Mom's "no" meant "No!"

     But several weeks later, opportunity knocked. My parents were going out for the evening. I

immediately invited Hanna to be my partner in bread-baking crime.

     We studied the recipe. That was easy. "Mix oil into flour then beat in four eggs, one at a time, with

remaining sugar and salt."

     We were not good at breaking eggs. I tried to learn from my mother.

     "Gradually add eight cups of flour. When dough (面团) holds together, squeeze it."

     We took turns working like that. "Is the dough 'holding together'?" we asked each other.

     I remembered my neighbor's instructions: "If it's too sticky, add some flour; if too dry, add water."

     We added water. Then more flour. Then more water. By then, the mass of our dough had grown very much.

     "Place dough on floured surface and squeeze till smooth," the recipe instructed.

     We took turns burying our hands in the damp dough, pinching, squeezing, and feeling it leak between

fingers. "Clean and oil bowl, and then return dough to bowl. Cover and let dough rise in a warm place for one hour."

     This was good news-we'd have a break. On the dirty kitchen chairs, we dreamed about our beautiful

bread. "See?" we would tell my mom. "Isn't it worth the work?"

     Hanna and I couldn't help glancing at the rising process every few minutes. But nothing happened.

     "Maybe something will happen in the hot oven," I said.

     Unfortunately, when we removed the loaves from the oven, they were like hard stones.

     Mom was right; it takes time and effort. It sometimes makes a mess. But still it feels good, somehow, to be part of that long, ongoing chain of bread bakers. Since that night, both Hanna and I have learned to do

it right.

1. To the writer, what her mother said was _________.

A. law

B. rubbish

C. advice

D. warning

2. Which of the following can best describe the children's feelings while making their first bread?

A. Confident; hopeful;proud  

B. Curious; hopeful; disappointed

C. Interested; excited; satisfied  

D. Worried; satisfied; proud

3. Which of the following did the writer do without referring to the instructions?

A. Placed dough on floured surface.    

B. Added eight cups of flour to eggs.

C. Returned dough to a cleaned bowl.  

D. Placed the dough into the hot oven.

4. The passage mainly tells us ___________.

A. the process of making bread          

B. the conflict between mother and daughter

C. the first experience of making bread    

D. the way of doing housework

问答题 简答题