① already可用于疑问句中，放在句尾，表示"惊讶，怀疑"。

Has he arrived already?他已经到了?(真没想到)

Have you finished supper already?

It's only half past five. 你已经吃过晚饭了?才五点半呢。

② still意为"仍然，还"，表示某事正在进行中或正在过程中，用于进行时或一般现在时，且常用于肯定句，有时也用于疑问句和否定句。

They are still talking in the room. 他们仍在房间里谈话。

She is still very young. 她仍然很年轻。

Is he waiting still?他还在等吗?

比较

He is still sitting. 他仍然坐着。

(still表示"仍然")

He is sitting still. 他坐着不动。

(still表示"不动的")

③ not...yet表示"还没有"，也常用于完成时，有时用一般现在时。

He hasn't done his homework yet. 他还没有做完家庭作业。

She isn't home yet. 她还没有到家。

提示

yet可用于由although引导的让步状语从句中，表示"但是";yet也可用作连词，引导从句，表示"然而"。

Although he tried his best，yet he didn't win the game. 虽然他尽了最大努力，但没能赢得那场比赛。

She wanted to come，(and)yet she was ill. 她想来，可是她病了。(如果用and yet，yet就是副词)

比较

Have you heard the news yet?(一般询问)

Have you heard the news already?(表示惊讶)

Is she here yet?她来了没有?(=Has she arrived?)

Is she still here?她还在这里吗?(=Hasn't she left?)