Why do plants grow in some places and not in the others? 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.

如图1为人体循环示意图，图2为人体某结构的血液流动情况示意图，A、C代表血管，B代表某结构，据图回答问题．

***曾对美国记者斯诺说：“从城市的观点来看，这个运动似乎是注定要失败的，因此中央委员会这时就明确的指责我。我被撤销政治局常委的职务。湖南省委也攻击我们，说我们是枪杆子运动”。材料中的“这个运动”（  ）