You use yet in negative statements to indicate that something has not happened up to the present time, although it probably will happen. You can also use yet in questions to ask if something has happened up to the present time.
They haven't finished yet.
他们还没有结束。
No decision has yet been made.
尚未作出决定。
She hasn't yet set a date for her marriage.
她尚未定下结婚的日子。
You use yet with a negative statement when you are talking about the past, to report something that was not the case then, although it became the case later.
There was so much that Sam didn't know yet.
还有很多是萨姆当时不知道的。
If you say that something should not or cannot be done yet, you mean that it should not or cannot be done now, although it will have to be done at a later time.
Don't get up yet.
还不要起床。
The hostages cannot go home just yet.
人质目前还不能回家。
You use yet after a superlative to indicate, for example, that something is the worst or the best of its kind up to the present time.
This is the network's worst idea yet.
这是到目前为止该网络最糟糕的点子。
Her latest novel is her best yet.
她的最新小说是她迄今为止最好的一部。
You can use yet to say that there is still a possibility that something will happen.
Like the best stories, this one may yet have a happy ending.
就像最精彩的故事一样,这个故事可能仍有个美好的结局。
You can use yet after expressions that refer to a period of time, when you want to say how much longer a situation will continue for.
Unemployment will go on rising for some time yet.
失业人数还会在一段时间内继续增长。
Nothing will happen for a few years yet.
几年内还不会有什么事发生。
If you say that you have yet to do something, you mean that you have never done it, especially when this is surprising or bad.
She has yet to spend a Christmas with her husband.
她还不曾与丈夫共度过一个圣诞节。
You can use yet to emphasize a word, especially when you are saying that something is surprising because it is more extreme than previous things of its kind, or a further case of them.
I saw yet another doctor.
我又看了一位医生。
They would criticize me, or worse yet, pay me no attention.
他们会批评我,或者更糟糕的是,可能会对我不理不睬。
You can use yet to introduce a fact that is rather surprising after the previous fact you have just mentioned.
I don't eat much, yet I am a size 16.
我吃得不多,但是却穿16码的衣服。
as yet
You use as yet with negative statements to describe a situation that has existed up until the present time.
As yet it is not known whether the crash was the result of an accident.
目前尚不清楚撞车是否是由事故引起的。