glad: may convey polite conventional expressions of pleasure: we are so ~ you could come; or it may convey the idea of an actual lifting of spirits, delight, or even elation: a face that makes me ~.  （pleasure愉快，强调满意，而不是表现在外的幸福快乐stresses satisfaction or gratification rather than visible happiness，如take pleasure in one's possessions为自己拥有财产感到愉快满意)  （delight喜悦和pleasure相反，强调是表现在外的幸福快乐stresses lively expressions of satisfaction，如the delight of grandparents in a new grandchild祖父母对孩子降临的喜悦）  （elation兴高采烈喜气洋洋，程度更强applies to a feeling of great happiness and excitement，如reacted to the news with elation听到消息后兴高采烈，如universal celebrations are held and the whole nation is in elation普天同庆万众欢腾)
  

happy: implies a sense of well-being and complete content: nothing made him so ~ as to be at home with his family.  （well-being福祉福利，表示总体上健康和幸福general health and happiness，如emotional/physical/psychological well-being情绪/身体/心理健康，如they have a sense of well-being他们感到幸福）  （content知足，是知足常乐的知足，表示虽然有遗憾，但大体能够认可接受不再抱怨，satisfaction是完全满意满足，但这里用了complete content完全知足，就是满意满足）


cheerful: suggests a strong spontaneous flow of good spirits: broke into a ~ song as he strode along.   (cheers祝酒干杯，cheer up打起精神、振作to become cheerful，如I wrote that song just to cheer myself up我写那首歌给自己打气，如cheer up, boy!振作起来,小伙子!如cheer up, better times may be ahead打起精神来,好日子还在后头。表示给体育队加油用cheer on，如their fans cheered them on from the sidelines支持者站在两旁加油，或直接用名词three cheers for our team为我们球队喊三次加油==hooray for our team，cheerleader是啦啦队长）  


lighthearted: stresses freedom from worry, care, and discontent: went off to school, ~ and gay. 和gay是同义词


joyful: usually suggests an emotional reaction to a situation that calls forth rejoicing of happiness or elation: heard the news with a ~ heart.  （rejoice表达欢乐to express great happiness about something,如there was general rejoicing at the news听到这一消息大家普遍感到欢喜, 如don't rejoice so soon且慢高兴）


joyous: is more likely to apply to something that is by its nature filled with joy or a source of joy: sang song after ~ song.


glad高兴: 既表示通常的礼貌性地表示愉快，也可指实际的高兴喜悦甚至欢腾，happy幸福快乐: 幸福表示快乐健康满足，cheerful欢快:  指源源不断的由衷而发的精神愉悦, lighthearted无忧无虑: 没有焦虑担忧不满，joyful感到快乐: 表示某人感到快乐幸福喜悦，joyous让人快乐: 表示某物使人快乐，或充满快乐


记忆方法: 1）首字母GHCLJJ想成GCHLJJ高唱欢乐京剧<==快乐

         2）练习一下  

         3）快乐的意思是心情愉快喜悦mean characterized by or expressing the mood of one who is pleased or delighted.首字母GHCLJJ想成GCHLJJ高唱欢乐京剧<==快乐