产生冷热裂纹的主要原因有（）。 A.铸件的厚薄不一 B.合金本身的原因 C.铸型的冷

阅读理解。

    There are many wetlands in China and some of them have become the world's important wetlands. The

Chinese Yellow Sea Wetlands are among them. They are in Yancheng, Jiangsu Province. They are home for

many different kinds of birds and animals. The world's largest Milu Deer Nature Reserve is in them. More

than 700 milu deer live freely there. There are not many red-crowned cranes in the world, but every winter

you can see some in the Red-crowned Cranes Nature Reserve in the Yellow Sea Wetlands.

    The temperature in the wetlands is usually neither too high nor too low. There is a lot of rain and sunshine,

too. They are really good places for wildlife. Offering food and home for some special kinds of animals and

birds is not the only reason why we need to protect wetlands. Wetlands are important because they also

prevent flood. But some people want to change the wetlands to make more space for farms and buildings.

This means there will be less and less space for wildlife.

    Luckily, more and more people are beginning to realize the important of wetlands and wildlife. Every year,

on February 2nd, many activities are held to tell people more about wetlands.

1. The Chinese Yellow Sea Wetlands are in the            of China. [ ]

A. east

B. south

C. west

D. north

2. The World Wetlands Day is on           . [ ]

A. April 22

B. June 25

C. February 2

D. March 22

3. We must protect wetlands because           . [ ]

A. they are home for wildlife

B. they can prevent flood

C. they can offer food to the animals and birds

D. all of the above

4. The best title for the passage is           . [ ]

A. China's Wetlands Have All Entered the World's List

B. Wetlands-Home for Wildlife and Human Beings

C. Special Animals in the Chinese Yellow Sea Wetlands

D. Wetlands-Valuable Recourses (珍贵资源) of Land on the Earth

社会角色规定着角色扮演者的权利与义务，因此，它对个人意味着限制、负担。

简述DT语音测试时模板设置？

下述哪个是非离子型对比剂

A．泛影葡胺
B．碘必乐
C．异泛影葡胺
D．泛影钠
E．碘化油

气体搅拌法即在自然投入法的基础上，向铁水表面吹压缩空气加强搅拌，以促进熔剂脱硅反应进行。