请认真阅读下列短文，从短文后各题所给的A、B、C、D四个选项中，选出最佳选项。
A
    If you travel by air across the center of Africa or South America, you fly over forests for thousands of kilometers. These great forests are the oceans of trees. There are full of thousands and thousands of different kinds of plants and animals.
    However, the world's forests are getting smaller all the time. We are cutting down the trees because we need wood, and we need more farm land. Some people say that there will not be any forests like these in 20 or 30 years. what will happen if they disappear?
    If we cut down our forests, a lot of plants and animals will disappear from the world. In a lot of places the new farm land will soon look like the old deserts. Crops will not grow there. It will not rain very often, and the weather will get very hot. Perhaps the climate of the world will change. This will be dangerous for everyone in the world. That is why we must take care of our forests.

如下曲线所示，甲商品的数量（Q）随着价格（P）的变动而变动，这可能说明的关系是（   ）

①甲商品的供给量（Q）与自身价格（P）

②甲商品的需求量（Q）与自身价格（P）

③甲商品的需求量（Q）与其互补品的价格（P）

④甲商品的需求量（Q）与其替代品的价格（P）

读 “我国四大地理区域示意图”，完成以下小题。

【小题1】图中的①、②、③、④分别代表我国四大地理区域，其中水热资源最丰富的是

A．①

B．②

C．③

D．④

【小题2】图中椭圆甲、乙、丙、丁中，交通网比较稠密的是

由代数式的乘法法则类比推导向量的数量积的运算法则：

①“mn=nm”类比得到“ $a\cdot b=b\cdot a$ ” ；

②“ $\left(m+n\right)t=mt+nt$ ”类比得到“ $\left(a+b\right)\cdot c=a\cdot c+b\cdot c$ ” ；

③“ $\left(m\cdot n\right)t=m\left(n\cdot t\right)$ ”类比得到“ $\left(a\cdot b\right)c=a\left(b\cdot c\right)$ ” .

以上式子中，类比得到的结论正确的个数是（    ）

设m，n为两条直线，为两个平面，则下列四个命题中，正确的命题是（   ）