Another way to talk about different types is to think about which ion they're selected for.

另一种方法是通过,看它们是针对哪种离子的。

麻省理工公开课 - 化学原理课程节选

0 were selected for the course with 5 alternatives.

其中35人参与该课程,5人用作备选。

麻省理工公开课 - 媒体、教育、市场课程节选

Solon was now a man of full years, he was a man greatly respected, and he turns out to be one of the seven sages that the ancient Greeks selected for the wisest men who ever were.

梭仑那时年岁已高并且备受崇敬,他最后被选为古希腊历史上,最具智慧的七个智者之一

耶鲁公开课 - 古希腊历史简介课程节选

With a different volatility for the stocks because that was also selected randomly, plus some market bias.

或者均匀分布的一个随机值,因为数值选择上的随机性，再加上市场偏好。

麻省理工公开课 - 计算机科学及编程导论课程节选