有许多不同种类的PSTN信令，包括在本地交换之间信号。

There are many different kinds of PSTN signaling, including signaling between local exchanges.

youdao

角培养科学信息交换之间的科学家和工程师在美国和外国的国家。

Foster the interchange of scientific information among scientists and engineers in the United States and foreign countries.

youdao

碳循环是循环中，碳是交换之间的水，大气，生物圈，地圈的地球。

The carbon cycle is the cycle in which carbon is exchanged between the hydrosphere, atmosphere, biosphere, and geosphere of the Earth.

youdao

There's no change in them, and then we also looked at some at non-state functions, work and heat, and saw that those aren't zero going around a cycle. Of course you can do work in a cyclic process, and heat can be exchanged with the environment at the same time.

它们不会有变化，然后我们研究了,一些非态函数，功和热量，并看到,沿着循环行进一周的话,它们并不是零，当然你可以在,一个循环过程中做功，而同时热量可以在系统,与外界环境之间进行交换。

麻省理工公开课 - 热力学与动力学课程节选