既是氧化还原反应，又是吸热反应的是 A．氢气在氧气中燃烧 B．铝片与稀硫酸反应

人感染卫氏并殖吸虫病主要是由于（）

A.生食或半生食淡水鱼虾

B.生食或半生食淡水螺类

C.生食或半生食水生植物

D.生食或半生食石蟹

E.以上均不是

用适当的冠词a,an,the或"／"填空

1. This is____useful book. I've read it for hour.

2. _____elephant is much heavier than ____horse.

3. _____doctor told him to take______medicine three times____day.

4. Let's go out for _____walk.

5. There is____woman over there.____woman is Meimei's mother.

6. ____sun rises in_______east.

7. ______Changjiang River is______longest river in_______China.

8. Are you going to do it____second time?

营养性缺铁性贫血的预防措施是

A．母乳喂养

B．预防感染

C．注意饮食卫生

D．多晒太阳

E．及时添加含铁丰富的辅食

胎儿血循环中血氧含量最高的部位

A．肺动脉

B．肺静脉

C．右心房

D．右心室

E．主动脉

喷淋室用循环水喷淋空气，这一空气状态变化为（）过程