The act said the purpose was to "conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations."

VOA: special.2009.09.28

Construction is a combination of workmanship and choice of materials. Take this computer, if I pull the silicon out, I replace it with gallium arsenide, leave everything else the same.

构造则是技巧和材料的选择,的结合，拿这个电脑为例，如果我将硅取出，替换成砷化镓，其他东西不变。

麻省理工公开课 - 固态化学导论课程节选