When we talk about p orbitals the phase of the orbital becomes important once we talk about bonding, which hopefully you were happy to hear at the beginning of class we will get to soon.

对于ｐ轨道,当我们讨论到成键时，轨道的相位就变得非常重要了,这个我们马上就要讲到了。

麻省理工公开课 - 化学原理课程节选

And in terms of thinking about the phase of this p orbital, the phase is going to be positive anywhere where z is positive.

对于ｐ轨道的相位，在ｚ大于零的地方都是正的。

麻省理工公开课 - 化学原理课程节选