q1 The heat input is just q1, Q and we'll define that as capital Q.

输入的热是，我们把它定义为大写的。

麻省理工公开课 - 热力学与动力学课程节选

get back to the initial point is going to require some input from outside, like heat or extra work or extra heat or something because you've done an irreversible process.

如果要逆转它,回到初始点，就需要外界的投入，比如额外的功，额外的热量等等,因为你进行了一个不可逆过程。

麻省理工公开课 - 热力学与动力学课程节选