简述牙轮钻头破岩工作原理？

下表为某品牌燕麦片标签的一部分

（1）上表出现了六大类营养素之中的_________类。

（2）上表出现了__________种人体所需的微量元素。

（3）人体健康离不开钙元素，下列有关钙元素的叙述不正确的是（填序号）_________。

a．人体中钙元素大部分存在于骨骼和牙齿中

b．幼儿缺钙会得佝偻病

c．老人缺钙会骨质疏松，易骨折

d．成年人比幼儿需要摄入更多的钙

引起牛的慢性增生性肠炎，表现为卡他性肠炎，长期间歇性顽固性腹泻，极度消瘦。特征性病变为肠黏膜高度增厚并形成皱襞，在皱襞褶中藏有大量成堆的抗酸性杆菌，但无结核或溃疡。该病病原可能是（）

A.结核分支杆菌

B.布鲁氏菌

C.副结核分支杆菌

D.沙门氏菌

E.衣原体

Ⅲ. 阅读（共两节，满分40分）

第一节　阅读理解（共15小题；每小题2分，满分30分）

阅读下面短文，掌握其大意，然后从41—55各题所给的四个选项（A、B、C、D）中，选出最佳选项，并在答题卡上将该项涂黑。

Although April did not bring us the rains we all hoped for, and although the Central Valley doesn’t generally experience the sound and lightning that can go with those rains, it’s still important for parents to be able to answer the youthful questions about thunder and lightning.

The reason these two wonders of nature are so difficult for many adults to explain to children is that they are not very well understood by adults themselves. For example, do you know that the lightning we see flashing down to the earth from a cloud is actually flashing up to a cloud from the earth? Our eyes trick us into thinking we see a downward motion when it’s actually the other way round. But then, if we believed only what we think and we see, we’d still insist that the sun rises in the morning and sets at night.

Most lightning flashes take place inside a cloud, and only a relative few can be seen jumping between two clouds or between earth and a cloud. But, with about 2,000 thunderstorms taking place above the earth every minute of the day and night, there’s enough activity to produce about 100 lightning strikes on earth every second.

Parents can use thunder and lightning to help their children learn more about the world around them. When children understand that the light of lightning flashing reaches their eyes almost at the same moment, but the sound of the thunder takes about 5 seconds to travel just one mile, they can begin to time the interval(间隔) between the flash and the crash to learn how close they are to the actual spark(闪光).

1. According to the author, in the area of the Central Valley, ___________.

A. rains usually come without thunder and lightning

B. it is usually dry in April

C. children pay no attention to the two natural wonders

D. parents are not interested in thunder and lightning

2. We believe that lightning is a downward motion because ___________.

A. we were taught so by our parents from our childhood

B. we are taken in by our sense of vision

C. it is a common natural sight

D. it is a truth proved by science

3. What is TRUE about lightning according to the passage?

A. Only a small number of lightning flashes occur on earth.

B. Lightning travels 5 times faster than thunder.

C. Lightning flashes usually jump from one cloud to another.

D. There are far more lightning strikes occurring on earth than we can imagine.

4. The underlined word “activity” is most closely related to the word(s)___________.

A. “cloud”                                       B. “lightning strikes”        

C. “lightning flashes”                              D. “thunderstorms”

5. It can be concluded from the passage that____________.

A. we should not believe what we see or hear

B. things moving downward are more noticeable

C. people often have wrong ideas about ordinary phenomena (现象)

D. adults are not as good as children in observing certain natural phenomena

决定过敏性紫癜预后的关键因素是（）

A.关节炎

B.腹痛剧烈

C.皮肤紫癜严重

D.伴发感染

E.肾脏损伤及其程度

水平测试