tpo1阅读求助！！感谢

makeithappenUID: 2585223

At the upper timberline the trees begin to become twisted and deformed. This is particularly true for trees in the middle and upper latitudes, which tend to attain greater heights on ridges, whereas in the tropics the trees reach their greater heights in the valleys. This is because middle- and upper- latitude timberlines are strongly influenced by the duration and depth of the snow cover. As the snow is deeper and lasts longer in the valleys, trees tend to attain greater heights on the ridges, even though they are more exposed to high-velocity winds and poor, thin soils there. In the tropics, the valleys appear to be more favorable because they are less prone to dry out, they have less frost, and they have deeper soils.
8. According to paragraph 3, which of the following is true of trees in the middle and upper latitudes?
○Tree growth is negatively affected by the snow cover in valleys.
○Tree growth is greater in valleys than on ridges.
○Tree growth on ridges is not affected by high-velocity winds.
○Tree growth lasts longer in those latitudes than it does in the tropics.

有没有人知道为什么要选1啊。。
我感觉是正面的影响啊 就是雪越大，数长得越高

wyacUID: 2633619

这是你臆断的，托福阅读最重要的一点是要忠于原文，不要加入自己的想法！
这一段涉及2对相对的概念：the middle and upper latitudes对the tropics；valleys对ridges.
第三段主要阐述了，在中高纬度，长在山脊的树比长在山谷的更高，而在热带地区则相反，原因是，中高纬度的树are strongly influenced by the duration and depth of the snow cover.山谷的雪deeper and lasts longer，所以 树在山脊长的更高：trees tend to attain greater heights on the ridges.
理解了这中间的逻辑关系，可以发现只有1正确，即在中低纬度的山谷中树的成长受到雪的负面影响。

makeithappenUID: 2585223

谢谢 只是不明白 树在山脊中长高为什么会是 负面影响呢

wyacUID: 2633619

你可能不理解山脊和山谷的意思，你可以简单的理解成前者是山顶，后者是山底，注意区分。选项1说的是山谷，树在山谷长的矮，自然是受负面影响了！

jedI5UID: 2720282

WYAC解释的真好  顶一下！

应小呆UID: 3109940

树受到负面影响才被迫长高的