Choose the best answer (根据短文内容，选择最恰当的答案）：

When the weather is hot, you go to a lake or an ocean. When you are near a lake or an Ocean, you feel cool. Why? The sun makes the earth hot, but it cannot make the water very hot. Although the air over the earth becomes hot, the air over the water is still cool. The hot air over the earth goes up. Then the cool air over the water moves in and takes the place of the hot air.

Then you may ask, “Why is the ocean full of salt?” Scientists will say that the salt comes from the rocks. When the rocks get very hot or very cold，they crack (爆裂）.Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. And then you may doubt, "But the ocean does not get more salty every year.，，Scientists are not sure about the answer to this question.

We know a lot about our world. But there are still many answers that we do not have, and we are curious about them.

【1】When the weather is hot, the sun makes hot.

A. the water B. the earth C. the river D. the ocean

【2】Scientists say that the salt in the ocean comes from the .

A. air B. rain C. water D. rocks

【3】Now scientists know .

A. the reason why the ocean does not get more and more salty every year.

B. what makes people feel cool near a lake or an ocean.

C. everything about our world.

D. what makes people feel cool near a lake or an ocean in summer.

【4】A rock cracks when .

A. it becomes very hot or very cold B. rain falls

【5】Which is TRUE according to the article?

A. While the hot air goes down, the cool air takes the place of it.

B. Whenever you feel hot, you can go to a lake or an ocean.

C. Ocean is full of salt.

D. The salt in the earth is carried by the sun.

【6】What’s the main idea of this passage?

A. Scientists can explain everything we want to know.

B. Scientists can explain many things, but not everything.

C. People always feel cool when they are near a lake or an ocean.

D. The salt in the ocean comes from the rocks.