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

All four of these hydrogens are electron-deficient in the same manner.

四个氢都是,以相同的方式缺电子。

麻省理工公开课 - 固态化学导论课程节选