笑只是一种表情，跟快乐没关系。
英文翻译：Laughter is just an expression. It has nothing to do with happiness.
重点词汇释义：
Laughter：大笑; 笑，笑声; 〈古〉好笑的事; 〈美俚〉力量悬殊得可笑的体育比赛
just：正好; 刚才; 仅仅，只是; 刚要; 公正的，合理的; 恰当的; 合法的; 正确的
expression：表现，表示，表达; 表情，脸色，态度，腔调，声调; 式，符号; 词句，语句，措辞，说法
has nothing to do with：无关
happiness：幸福; 高兴; 快乐; 恰当; 合适
只是
英文：just; only; merely; simply; however
表情
英文：expression; look; countenance; express one's feelings; brow
没关系
英文：It doesn't matter.; It's nothing.; That's all right.; no sweat [美俚]; never mind