already和yet的区别：

1、常用句型不同

already多用于肯定句,而yet多用于疑问句或否定句。


The authorities believe those security measures are already paying off


当局相信那些安全措施已经奏效。

《柯林斯高阶英汉双解学习词典》


"Have they been to visit you yet?" — "Just the once, yeah."

“他们来看过你吗?”——“来过,就一次.”

The worst of the storm is yet to come.

最猛烈的暴风雨就要来了。

Life has not yet returned to normal but we are getting there.

生活还没有恢复正常，不过就快了。

‘Lunch?’ ‘No thanks, I've already eaten.’

“午餐？”“不，谢谢，我已吃过了。”

We got there early but Mike had already left.

我们及早到了那里，但是迈克已经离开了。

I already did it.

我已经完成了。

Did you eat yet?

你吃饭了吗？

在北美英语中还可与简单过去时连用

2、不常用句型意思不同

already有时也可用于疑问句中表示惊讶、怀疑,或者表示期望〔预计〕有一个肯定的回答。

yet有时也可用于肯定句中,意思与still相同(仍然,还; 迟早),而与already不同

1.He was already asleep in the bed, which smelled faintly of mildew.

他已经在略带霉味的床上睡着了。（美国英语常用）

2.The material consisted only of already published, unclassified information.

这份材料里只有一些已公开的、非保密性质的信息。（美国英语常用）

3.The country's politicians are already heaving a collective sigh of relief.

该国的政界人士均已松了口气。

4Truck owners are already making the switch.

车主们已经开始改弦更张。

5.But it's already happened a lot overseas.

但在美国以外的很多市场早就在这么做了。

6.Have you already seen him?你已经看见了他吗？（表示期望〔预计〕有一个肯定的回答。）

7.Have you finished your composition already ?You are very speedy.

你已经完成了你的作文了吗？你真神速啊！（表示惊讶等感情色彩）

already常用于强调或暗示某件事的发生快得令人惊奇：They were already eating their lunch（他们已经在吃午饭了）

8.Is it 10 o'clock already?

都10点钟了？（表示惊奇）

9.You're not leaving already, are you?

你已经不打算走了，是不是？（表示惊奇）

10I'm already late.

我已经迟到了。（强调情况或问题存在）

11.There are far too many people already. We can't take any more.

已经有太多的人了。我们再也接待不了啦。（强调情况或问题存在）

拓展


already常用于强调或暗示某件事的发生快得令人惊奇：

They were already eating their lunch（他们已经在吃午饭了）。

still可用来强调对某件事发生或持续如此长时间感到惊奇：

She was still looking at me（她还在看着我），

There are still plenty of horses round here（这附近还有很多匹马）。

yet常用在否定句和疑问句中表示强调，或对某事还未发生表示惊奇，或表示某事将要发生：

Have you seen it yet（你看过了吗）

The troops could not yet see the shore（部队还是看不见海岸）

It isn't dark yet（天色还没有暗下来）。

英国英语中already和yet通常用于现在完成时：

I have already started knitting baby clothes(我已经开始织婴儿衣服了）

Have they said sorry yet（他们道过歉了吗）。

美国英语中，常用于过去时：

She already told the neighbors not to come（她已经告诉邻居们别来了）

I didn't get any sleep yet（我还没合过眼）。

这种用法在英国英语中也越来越普遍。