下列关于弹力的说法中,正确的是() A.木块放在桌面上对桌面产生的压力,是由于木

题型:选择题

问题:

下列关于弹力的说法中,正确的是(   )

A.木块放在桌面上对桌面产生的压力,是由于木块发生微小形变而产生的

B.用细竹竿拔动水中的木头,木头受到的弹力由于木头发生形变而产生的

C.细绳对物体拉力的方向总是沿绳而指向绳收缩的方向

D.挂在电线下面的电灯受到竖直向上的拉力,是因为电灯发生微小形变而产生的

考点:弹力的产生、方向和种类弹力的大小、胡克定律
题型:选择题

阅读理解。

     Zhao Tao, a student from No.2 Middle School, has just come back from Shanghai. This morning, he told

us something about his pleasant trip. When he talked about the Shanghai World Expo (上海世博会), he was

so excited and so proud that he kept telling about it for several hours. The Shanghai World Expo held by China

has been on for more than one month.It started on May 1st,and will end on October 31st,2010. Its main idea

is "Better City, Better Life." About 242 countries and organizations are attending (参加) this expo. Many new

products can be seen here, such as we can see the snow in the South Korea Corporate Pavilion(展馆) every

day during this hot summer though it seldom snows in Shanghai. And we can see, hear, touch and smell the

4-D films at the Oil Pavilion. How wonderful all these new products are!

     China Pavilion is in the center of the expo garden. It is very beautiful. It represents the development of China

from ancient time to now. It's a pride of our China!

     Thousands of people from all over the world are coming to the expo every day. And many volunteers are

working for them. All the tourists are very pleased and they say that the Shanghai World Expo is the greatest

one in the world so far.

     However, Zhao said, "The expo garden is now so crowded. If you want to visit it, you'd better go there

during the summer vacation."

1. The main idea of the Shanghai World Expo is "_____".

A. Better City, Better Life.

B. How to Protect the Environment.

C. No War in the World.

D. No Earthquake.

2. In which pavilion can we see the snow during this hot summer?

A. China Pavilion.

B. the Oil Pavilion.

C. the South Korea Corporate Pavilion.

D. I don't know.

3. So far, how long has the Shanghai World Expo been on?

A. For 20 days.

B. For a month.

C. For four weeks.

D. For about 50 days.

4. How many countries and organizations are attending the Shanghai World Expo?

A. 150.

B. Less than 180.

C. 242.

D. 220

5. Which of the following is NOT talked about in this passage?

A. Zhao Tao is a middle school student.

B. China's new products are excellent.

C. The volunteers are working very hard.

D. The expo garden is now very crowded.

题型:选择题

病毒能否吸附易感细胞的决定因素是()

A.病毒包膜

B.核酸

C.刺突

D.壳粒及排列

E.病毒表面的配体位点和敏感细胞表面的特异性受体

题型:选择题

某泥地能承受的压强为400Pa。小明的体重为500 N,他每只鞋接触地面的面积为1.25×10-2m2,为了不让脚陷进泥地,他在泥地上放一块重为100 N的木板,当他双脚站在木板中央时,木板恰好没有陷进泥地。求:

(1)他对木板的压强;

(2)木板与地面的接触面积。

题型:选择题

下列有关轻钢龙骨、铝及铝合金的叙述,哪一项不正确?

A.轻钢龙骨以镀钵钢带或薄钢板由特制轧机轧制而成。可装配石膏板、钙塑板、吸声板等用作墙体和吊顶的龙骨支架,但不能作悬挑阳台的支架

B.上人的吊顶轻钢龙骨CS60的壁厚是0.63mm

C.铝合金门窗的名称中通常以系列表示,系列是指铝合金门窗框料断面的宽度

D.铝及铝合金箔可用于保温隔热、隔汽及作装饰材料等

题型:选择题

心肺复苏时的用药目的中,不包括()。

A.激发心脏复跳并增强心肌收缩力

B.防治心律失常

C.调整急性酸碱和电解质失衡

D.补充血容量

E.预防感染

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