1.sandstone n.沙岩
2.rebel vi.造反, 反抗, 抵抗, 反感
例句：How can you rebel against your seniors?
你们这些晚辈，怎么能忤逆长者？
3.heal v.使复原, 使和解, 治愈
例句：The doctor said he must avoid excitement in order for the disease to heal.
医生嘱咐他一定要静心安养。
4.underground a.地下的, 秘密的
例句：When we were doing underground work, he was my only contact.
做地下工作时，他和我单线联系。
1.It still is popular with people who live in West Virginia and visitors who have fallen in love with what is known as the Mountain State.
fall in love with爱上
例句：He that falls in love with himself will have on rival.
凡是爱上自己的人，都不会有情敌。
2.The rocks are very difficult to climb.
形容词+不定式
inessential（非必要的）和unimportant（不重要的）通常不这么用，但可以说not essential。
it＋be+形容词（＋for+宾语）+动词不定式结构中可以用下列形容词：convenient（便利的），dangerous（危险的），diffi－cult（困难的），easy（容易的），hard*（艰难的），possible*（可能的），impossible（做不到的），safe（安全的），unsafe（不安全的）。
Would it be convenient（for you） to see Mr X now？
（您）现在见X先生方便吗？
It was dangerous（for women） to go out alone after dark．
（妇女们）天黑以后单独出门是危险的。
We found it almost impossible to buy petrol．
我们发现几乎买不到汽油。
上述形容词除possible之外，均可用于名词+be+形容词+动词不定式结构中：
This cake is easy to make．
这蛋糕很容易做。
The instructions were hard to follow．
这指示很难遵从。
This car isn’t safe to drive．
这辆车开起来不安全。
3. The Forest Service is protecting the area from too much human activity so it will return to its natural wild condition.
so引导的从句在这里表是目的，相当于 so that.