The air is thin and we have to rest several times on the short hike from camp. To our left, snow-covered mountains disappear into clouds that seem almost close enough to touch. On the plain in front of us, we can just make out a herd of graceful animals. This is why we're here — to observe Tibetan antelopes.
clouds that seem almost close enough to touch 中 that 引导定语从句修饰 clouds。seem 是系动词，close enough to touch 作表语。
enough 的用法：adj./adv. + enough + to do 表示"足够……以至于能……"。如 old enough to go to school（够大可以上学）。
to observe 不定式表目的
to observe Tibetan antelopes 是不定式短语作目的状语，说明"为什么来这里"。破折号后面的不定式对前面进行解释说明。
不定式表目的可置于句首或句末，置于句末时更简洁。如：I came here to learn English.
Tibetan antelopes live on the plains of Tibet, Xinjiang, and Qinghai. Watching them move slowly across the green grass, I'm struck by their beauty. I'm also reminded of the danger they are in. They are being hunted, illegally, for their valuable fur.
Watching them move slowly across the green grass 是现在分词短语作时间/伴随状语，逻辑主语是 I（I watch them move...）。
注意：watch sb do sth 中 do 是不带 to 的不定式（省略to），强调看到动作全过程。比较：watch sb doing sth 强调看到动作正在进行。
are being hunted 现在进行时被动语态
They are being hunted 使用了现在进行时的被动语态（am/is/are + being + 过去分词），表示此刻正在被猎杀，或现阶段持续被猎杀。
进行时被动强调动作的持续性和当下性。比较：They are hunted（一般现在时被动）强调经常性/事实。
My guide is Zhaxi, a villager from Changtang. He works at the Changtang National Nature Reserve. The reserve is a shelter for the animals and plants of northwestern Tibet. To Zhaxi, the land is sacred and protecting the wildlife is a way of life. "We're not trying to save the animals," he says. "Actually, we're trying to save ourselves."
The 1980s and 1990s were bad times for the Tibetan antelope. The population dropped by more than 50 percent. Hunters were shooting antelopes to make profits. Their habitats were becoming smaller as new roads and railways were built.
In order to save this species from extinction, the Chinese government placed it under national protection. Zhaxi and other volunteers watched over the antelopes day and night to keep them safe from attacks. Bridges and gates were added to let the antelopes move easily and keep them safe from cars and trains.
keep them safe from attacks 中 keep + 宾语 + 形容词（宾补），表示"使……保持……状态"。safe from 表示"免受……的安全的"。
类似结构：keep the room clean（保持房间整洁）；keep the children away from danger（让孩子们远离危险）。
The measures were effective. The antelope population has recovered and in June 2015, the Tibetan antelope was removed from the endangered species list. The government, however, does not intend to stop the protection programmes, since the threats to the Tibetan antelope have not yet disappeared.
In the evening, I drink a cup of tea and watch the stars. I think about the antelopes and what Zhaxi told me. Much is being done to protect wildlife, but if we really want to save the planet, we must change our way of life. Only when we learn to exist in harmony with nature can we stop being a threat to wildlife and to our planet.