Experts at Penn State University say the answer is simple: when the undesirable qualities outweigh the good qualities.

VOA: special.2011.07.26

Let's try it with a different equation of state, that isn't quite as simple as the ideal gas case.

考虑一个不同的状态方程，这状态方程不像理想气体状态方程那么简单。

麻省理工公开课 - 热力学与动力学课程节选

Experts at Penn State University have a simple answer: When the undesirable qualities outweigh the good qualities.

VOA: special.2010.08.10

Instead,it will be based on a simple principle: whether a state is ready to do what works.

VOA: special.2009.07.30

Experts at Penn State University have a simple answer: When its undesirable qualities outweigh its good qualities.

VOA: special.2009.05.26

The ceremony was held under the pine trees with Stumpy saying the simple works: "I proclaim you Thomas Luck, according to the laws of the United States and the state of California, so help me God."

VOA: special.2009.06.06