The strength of a response tendency depends on the amount of reinforcement received.
The poor are not irrational; they are just as rational as anyone else, but they operate under very different constraints.
压力总是存在的，但我尽量不去想太多。我专注于比赛。
The world is in a constant state of flux. Nothing remains the same from one moment to the next. You can never step into the same river twice.
Sustainable development is not an option, but a necessity for the coal sector.
Three grand essentials to happiness in this life are something to do, something to love, and something to hope for.