典型支气管哮喘发作时的临床表现是（） A.吸气性呼吸困难及双肺哮鸣音 B.呼气性呼吸

winter-swimming has become popular in Beijing. three years ago, few people would go swimming in the city waters. but now there is a winter-swimming

enthusiasts’club(冬泳爱好者协会)and it has more than 2,000 members. the oldest is 84 years of age and the youngest is only 7. The members are from all walks of life. They may be workers, peasants, soldiers, teachers, students....Though it is now the coldest part of the season and the water temperature in the city’s lakes is around 0°c, many winter-simmers still swim in the icy waters, even when it is snowing. They enjoy themselves in the lake, while the people by the side of the lake are wearing heavy clothes.

why are so many people interested in winter-swimming? Because winter-swimming can be good for one’s health.

Bei Sha is a good example. He is 69 years old, and he once suffered from heart trouble for 26 years. After ten years of winter-swimming he is now in good health. Scientists are now studying the effects of winter-swimming on health.

小题1:Guess what “the members are from all walks of life” means ______   .

A．The members do different jobs at different places.

B．They come from all parts of Beijing.

C．They are persons of different ages.

D．They are men and women , old and young.小题2:Winter-swimming has become popular in Beijing because _______.

A．more and more people like to swim in winter

B．it is more interesting than swimming in summer

C．winter-swimmers are brave men

D．winter-swimming does a lot of good to one’s health小题3:The best title for this passage should be ______.

A．People in Beijing Like Swimming in Winter　　

B．Winter-Swimming-----A Craze(狂热) in Beijing

C．People Benefit from Winter-swimming

D．Winter-Swimmers are Brave Men

贮藏过程中引起中药酸败的化学成分主要为()。

A.油脂类

B.植物色素类

C.有机酸类

D.生物碱类

下列哪项与龈下牙石的形成有关（）

A.龈上菌斑

B.附着性龈下菌斑

C.非附着性龈下菌斑

D.白垢

E.食物碎屑

位于华北平原东北部，海河五大支流汇合处，三面与河北省接壤，西北部分两段与北京交界，东临渤海是（）。

A、天津

B、山西

C、山东

D、辽宁

注射用水为（）。

A.离子交换法制备的水

B.反渗透法制备的水

C.纯化水

D.纯化水经蒸馏所得的水

E.原水经灭菌所得的水