already多用于肯定句,表示一事实 意为 已经 早已
1.He had been released already since then.
自那之后他就被释放了.（肯定句）
2.We've already had the exam.
我们已考过试了.（肯定句）
yet则多用于否定句、疑问句,意为 还、尚、迄今、到那时
1.Have you got it yet?（疑问句）
你明白了么?/你收到了么?
2.I haven't had my car repaired yet and I anxiously need to repair it.我还没修车,我急需修好它.（否定句）