Why do plants grow in some places and not in other? Why does some land have so much growing on it, while other land has almost no plants growing on it at all?
To grow, plants need several things. One is warmth. In very cold places almost nothing grows. Plants also need water. In very dry parts of the Earth only a few unusual plants can grow. That's why dry deserts everywhere are almost not covered by trees or grass.
Plants must also have a place in which to put down their roots and grow. They find it difficult to grow on hard land. The town is built on hard land. The plants here have only the soil found between the cracks of the stones to grow in.
Another thing plants must have before they can grow is food.
What will happen if we try to make things grow on the sandy beach? A few plants, such as beach grass, will grow in sand, but most plants won't. Even if the weather is warm enough and we water the plants each day, many of them will die because the sand on this beach has almost no food for plants.
What does the underlined word "cracks" mean in the text?

A．缝隙	B．表面
C．夹层	D．底部

From the passage, we can know it is             for plants to grow in dry places.

A．easy	B．difficult
C．impossible	D．important

The reason why most plants can't grow on the sandy beach is that _______   .

A．there isn't enough sunlight

B．there is too much water

C．it is too crowded there

D．it has little food for plants

The passage can most probably be found in a ______  book.

A．science	B．history
C．travel	D．math