serotonin 血清素 mindset 心态，思维模式 adapt 改变以适应变化 easier said than done 说时容易做时难 energise 使精力充沛 grieve 伤心，难过. 测验与练习. 1. 阅读课文并回答问题。 1. What is it a lack of that affects the part of the brain that rules sleep, ...