They are also a good way to test if a local market for oil exists.

VOA: special.2009.09.29

I can build class stock, and I can test class stock, before I have a class market.

我可以建立一个stock类，然后在有macket类之前测试这个类。

麻省理工公开课 - 计算机科学及编程导论课程节选

I can build class stock, and I can test class stock, before I have a class market.

我可以建立一个stock类，然后在有macket类之前测试这个类。

麻省理工公开课 - 计算机科学及编程导论课程节选