经过中和箱处理的废水中仍然含有（）。A、Hg（汞）；B、Cr（铬）；C、Pb（铅）；

患者男性，72岁，失眠3年，需要长期口服镇静安眠药才能维持睡眠。

服用过量巴比妥类药物，应用碳酸氢钠的目的是

A．碱化尿液，促进药物排泄
B．影响药物的吸收
C．中和过量的药物
D．影响药物的分布 E．减少药物的吸收

阅读理解。

     In many cultures white is often associated with something positive. A white-collar job, for instance,

is the kind of job many people look for, working with your brain and not your hands.

     White has a clean and pure image.That is why doctors, dentists, and nurses usually wear white

uniforms. Babies are dressed in white at baptisms (洗礼) and brides wear white wedding gowns at

weddings.White in these cases is the symbol of innocence or purity.

     Sometimes white is used in expressions that are not good. "Whitewash" is one such expression.At

first, "whitewash" meant to paint over something with white paint to make it look better. However, it

means something different today: to hide or to cover up mistakes or failures.

     A "white elephant" is another example of white used in a negative way. In ancient Thailand, a white

elephant was regarded as a sacred animal, but it was very expensive to keep. The kings of those days

presented a white elephant to the people they wanted to ruin.Once they received this holy, royal animal

      as a gift, they were not allowed to sell or kill it.Today, a "white elephant" means something that is

big, useless, and unwanted. In America, when people want to get rid of their furniture or clothes, they

often have a "white elephant sale".

1. The text is mainly about _____.

A. the meanings of white in English culture

B. the history of some English idioms

C. some interesting customs in English culture

D. some useful English words and expressions

2. Which expression has an historical background?

A. White-wash.

B. White-collar.

C. White elephant.

D. White elephant sale.

3. In which statement does"white" have a negative meaning?

A. A boy is dressed in white at baptisms.

B. A bride wears a white wedding gown.

C. A man whitewashes his crime.

D. A girl finds a white collar job.

4. The author develops the text mainly by ______.

A. analyzing its cause and effect

B. providing typical examples

C. comparing different ideas

D. following the time order

生物正常体细胞染色体数目为8条，下图表示含有1个染色体组的细胞是（）

A.

B.

C.

D.

灌水率图的修正时，延长或缩短灌水时间与原定时间相差不应超过（）

A.15%

B.20%

C.25%

D.30%

进行治安巡逻是治安警察的职责。 ( )