already和yet的区别解析：
already “已经”（肯定句）
yet“已经”（一般疑问句）；“还”（否定句）

1.already 用于肯定句
already常在：have+ 动词过去分词的中间；或 句尾
I have already seen the movie.
= I have seen the movie already.
我已经看过这部电影了。
Emily has already had dinner.
=Emily has had dinner already.
艾米丽已经吃过晚饭了。

2.yet用于一般疑问句或否定句
常用于句尾
Have you seen the movie yet?
你已经看过这部电影了吗？
[yet在一般疑问句表示“已经”]
Has she completed the sentence yet?
她已经完成那个句子了吗？

I haven't seen the movie yet.
我还没有看过这部电影。
[yet在否定句中表示“还”]
He hasn't met Jackson yet.
他还没有见到杰克逊。

所以，already和yet的区别主要取决于用于肯定句，还是否定和疑问句。