Above the tree line there is a zone that is generally called alpine tundra.
Immediately adjacent to the timberline, the tundra consists of a fairly
complete cover of low-lying shrubs, herbs, and grasses, while higher up the
number and diversity of species decrease until there is much bare ground with
occasional mosses and linchens and some prostrate cushion plants. Some plants
can even survive in favorable microhabitats above the snow line. The highest
plants in the world occur at around 6,100 meters on Makalu in the Himalayas.
@@@ At this great height, rocks, warmed by the sun, melt small snowdrifts. @@@
要插入的句子
This explains how, for example, alpine cushion plants have been found growing
at an altitide of 6,180 meters.
兩個@@@都是選項
一個是正確答案 一個是我的錯誤選擇
正確答案是後者
我選了前者
請問是否有高人可解答?
感謝~~

關鍵字explain, 所以前一句要是因, The highest那句無法

我不太懂為什麼融雪可以解釋他的生長因為這樣才有水源?

是的。插入句裡有This, 一定是前面有說過的事情才會用this代替，所以插入句前面應該要有可以放在 this 這個位置的東西，而 this 代替的something 要能夠 explain (解釋) 為什麼alpine cushion 這種植物可以在很高的地方生長。你的第一個@@@前一句只說明了發現有植物生長的最高高度是喜馬拉雅山上6100公尺的地方而已，所以放這裡並不通順。最後一句說了在這高度的石頭因為會被陽光加熱，所以會融化少量降雪，而這件事才可以解釋植物可以在那麼高的地方生長。(融雪＝有水，是這樣子沒錯！）

好的 超清楚的解釋....感謝你