全部

1·In fact, according to a recent scientific study, overall levels of happiness decline from one's teens until one's 40s and then pick up again until they peak in one's early 70s.

事实上，据最近一项科学研究表明，所有快乐水平在少年时期至40岁之间会有所下降，而在70岁时达到顶峰。