Other plants take nitrogen out of the soil, but beans and other legumes replace it.

VOA: special.2009.03.24

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