Diplomats and observers warn that this could be the deadliest phase of the war, as the army tries to target the rebels mixed in the civilian population.

VOA: standard.2009.04.06

Once the gases are mixed, there's not going to be any further net change in the system.

一旦气体混合,这个系统就不会发生任何净的变化。

麻省理工公开课 - 热力学与动力学课程节选

So would you expect this to be a pi bond or a sigma bond her PROFESSOR: OK, so I'm hearing some mixed answers.

你们觉得这是一个π键还是sigma键？,我听到有不同的答案。

麻省理工公开课 - 化学原理课程节选