Because traditional economic theory would say, well, the mountain bike was probably invented by some big bike corporation that had a big R&amp;D lab where they were thinking up new projects, and it came out of there. It didn't come from there.
传统的经济理论会说， 嗯，山地车很有可能是某个大型自行车公司发明的， 因为它有一个很大的研发中心 来琢磨出新项目， 于是山地车就产生了。但是山地车不是从那里创造出来的。