如图中所示的三图原理，甲图根据____ 制成的；乙图根据____ 制成的；丙图表明了____ ．

Rainforest also help to ____   the weather. When trees are cut down, it gets hotter. Besides, one quarter of our ____  come from plants. Many of these plants can be found only in rainforests. There is a lot that we have not learnt about rainforests. If we____ them, we will never find out.

In my opinion, our future____ saving the rainforests. We must tell more people how important rainforests are so that they will stop doing harm to them. We must protect the rainforests now. We have to act now to save our only home.

分布于我国地形第二阶梯上的最主要两种地形为（　　）