以800N的集中载荷加压2h,其最大变形量应不大于()mm。
A.2
B.4
C.6
D.8
参考答案:D
写出下列反应的化学方程式和离子方程式:
(1)铁与硫酸铜溶液反应化学方程式:______;离子方程式:______.
(2)钠与水的反应化学方程式:______;
(3)碳酸钙与盐酸反应离子方程式:______.
第四部分:短文改错:10%
Besides Egyptians, people of Mexico also builded 41._____________
pyramids. They didn’t build the pyramids for tombs. They 42._____________
were used to build a pyramid and then build a temple on 43.____________
top of them. The pyramids of Mexico are not as high as 44.______________
that of Egypt, but they are big. Each pyramid has a wide 45.____________
stairway that go from the bottom to the top. 46._____________
The biggest pyramid in Mexico is almost 2000 year 47.___________
old. Scientists think it spent 10,000 men more than ten years 48.____________
to build. On top of it they build a temple to worship sun. 49.____________
The temple is no longer there and people call it the pyramid 50.____________
of the sun.