阅读理解。
Water is the "life" of our earth. It is in every living thing. It is in the air. It
runs through mountains and valleys. It forms lakes and oceans. Water is
everywhere.
Nature has a great water system. Rainwater finds its way to streams and
rivers. Rivers lead to the ocean. At mouths of rivers, fresh water joins the salt
water of the ocean.
Thick water steam in the air becomes clouds and clouds bring us rain. Plans
and animal's life depends on water. Where there is water, there is life. We have
to clean our streams and rivers and do something against pollution because
pollution does harm to the life.
1.We say water is the "life" of our earth because _______.
A. water is in the air
B. water can run everywhere
C. there are living things in the water
D. where there is water, there is life
2. Which of the following is exactly the same as what the article says?
3. According to the article, which of the following is correct?
A. Water is in every living thing.
B. Water is everything.
C. Water forms everything.
D. Water runs through everything.
4. According to the article, fresh water joins the salt water of the ocean .
A. in the valleys
B. in the mountains
C. at mouths of rivers
D. at mouths of oceans
5. What does this article say we have to do against pollution?
A. Clean the steam.
B. Stop air pollution.
C. Prevent the fresh water from joining the salt water.
D. Clean our streams and rivers.
-0.5)σcon=0.4×0.9×(0.7-0.5)×1204=86.7N/mm2
=12.90N/mm2