To say that somebody does something alone means they do it not in the presence of others.

就是说人孤独而死的意思是,他们死的时候身边没有别人的存在。

耶鲁公开课 - 死亡课程节选

You can say "Why don't you" when you want to suggest that somebody else do something.

当你想建议他人做某事时，你可以说“Why don't you~?”。

Why don't 课堂 - SpeakingMax英语口语达人

If somebody wants to believe something, I say what's the evidence for?

如果有人说他相信什么东西，我一定会问，有什么证据呢？

普林斯顿公开课 - 人性课程节选

Does somebody want to say something?

有人想说些什么么？

麻省理工公开课 - 电影哲学课程节选

If you think about the modern food environment compared to the ancient one, so let's say somebody getting something at a fair compared to the old days.

如果将现在的饮食环境,与过去的相比,例如比较在现在和过去的人们,在集市上能买到哪些东西

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

So, suppose you fall in love with somebody and you decide you want to marry them and then somebody was asked to ask you why and you'd say something like, " "Well, I'm ready to get married this stage of my life; " I really love the person; " the person is smart and attractive; I want to have kids" whatever.

假设你爱上了某人,想要与对方一同步入婚姻的殿堂,要是有人问你为什么想要与对方共度余生,你大概会说，“现在我已准备好要开始婚姻生活了;,或“我真心的爱着他;,或“他聪明有魅力;,“我想要小孩了“，等等。

耶鲁公开课 - 心理学导论课程节选