请问是she didn't do her homework,yesterday.还是she didn't do her

不是吧。这个根本不需要逗号啊、yesterday。是时间表示过去一般式的标志性时间词。eg my mom and I went shopping yesterday。你看我的例句和你的差不多,如果你说需要逗号那是画蛇添足。你可能不懂什么叫时间状语。学下去就会明白了~ 再问： 什么是时间状语啊 再答： 以时态来说吧。其实这个概念很好懂的，　时间状语就用来是表示时间的词或词组 时间状语 一般现在时 every …, sometimes, at …, on Sunday, 一般过去时 yesterday, last week, an hour ago, the other day, in 1982, just now 一般将来时 next…, tomorrow, in+时间, 现在完成时 for, since, so far, ever, never, just, yet, till/until, up to now, in past years, always, recently 过去完成时 before, by, until, when, after, once, as soon as 过去进行时 this morning, the whole morning, all day, yesterday, from nine to ten last evening… when, while 将来进行时 soon, tomorrow, this evening, on Sunday, by this time, tomorrow, in two days, tomorrow evening 这么说明白么？再问： 谢谢，懂了