constant level短语¹¹⁴⁴⁶⁷⁺⁴ 基本例句 恒定水准,常液面 As incomes in the U. S. tend to rise, individuals may find themselves on a treadmill, consuming more and more just to maintain a constant level of happiness. 由于美国的工资水平在断升高，人们回发现自己处在一个没有终点的跑步机上面，为了让自己快乐消费的越来越多。 cri