1. ALREADY
已经

Already is used to show that something has happened earlier. It is used in the mid-position of the sentence and is usually used with Present Perfect.
Already被用来表明早些时候发生了什么事。它用于句子的中间位置，通常与现在完成时连用。

In American English, it is also possible to use already with the Simple Past.
在美式英语中，也可以用一般过去时。

Already in a sentence:
Already用于一个句型中

other ways to say said
其他的说法

British English:
英式英语：

I have already done my homework./He has already washed the car.
我已经做完作业了。/他已经洗车了。

American English:
美式英语：

I already did my homework./He already washed the car.
我已经做完作业了。/他已经洗车了。

2. STILL
仍然

Still is used to show a continuous action, and is used in affirmative sentences. Still is used in the mid-position of the sentence. And is usually used with Present Continuous (Progressive).
Still用于表示连续动作，并用于肯定句。仍然用在句子的中间位置。通常与现在进行时连用。

Still in a sentence:
Still在一个句子中：

I am still doing my homework. /He is still washing his car.
我还在做作业。/他还在洗车。

Still requires the use of Progressive forms. Except for the verbs be, have and verbs of primary perception*. Or when you want to indicate a habitual situation (HABIT).
Still需要使用进行时。除了be，have和基本感官动词。或者当你想表明一种习惯性的情况（习惯）。

For example,
例如：

I still have the book that you gave me./I am still a strong guy./I can still hear< him./I still see her outside./ She still
我还有你给我的那本书。/我仍然是个强壮的人。/我仍然能听到他。/我仍然看到她在外面。/她仍然去公园里慢跑。–习惯/他仍然在目标店购物。–习惯

NOTE: still is rarely used in negative sentences. It is usually replaced by ‘not…anymore’ or ‘no longer’
注意：在否定句中很少使用still。它通常被“不再……不再”或“不再”

For example,
例如：

I no longer< have the book that you gave me./I am not a strong guy anymore.
我不再有你给我的那本书了。/我不再是一个强壮的人了。

Verbs of primary perception: see, hear, taste, smell, listen, feel, watch.
基本感官动词：看、听、尝、闻、听、摸、看。

3. YET
仍然

words to use instead of said. Yet is used to talk about something that is expected to happen, but did not happen till this moment. Yet means at any time up to now. Yet is used in interrogative (questions) and negative sentences. Yet is usually used with Present Perfect. Yet is used in the end of the sentence.
其他说法：Yet这个词是用来谈论预期会发生的事情，但直到现在才发生。但意思是到现在为止的任何时候。但用于疑问句和否定句。但通常与现在完成时一起使用。但在句子的结尾使用。

Yet in a sentence:
Yet在一个句子中：

Have you finished your homework yet? – Interrogative/I haven’t washed my car yet. – Negative
你做完作业了吗？–疑问/我还没洗车。–否定

Yet is very rarely used in affirmative sentences, but when it is used, it implies a negative.
Yet在肯定句中很少使用，但当它被使用时，它意味着否定。

For example,
例如，

I have yet to read the ‘Harry Potter and the Goblet of Fire’ book= I have not read the ‘Harry Potter and the Goblet of Fire’ book yet, but I will probably read it soon.
我还没有读过《哈利波特与火焰杯》这本书，但我可能很快就会读到。

4. JUST
仅仅

Just is used when we want to say that something happened a short time ago (very recently).
当我们想说不久前（最近）发生了什么事情时，就使用Just。

It is always used with Present Perfect or Past Perfect. It is used between the auxiliary verb (have/has) and past participle. Just can be used in affirmative and interrogative sentences.
它总是和现在完成或过去完成一起使用。它在辅助动词（有或有）和过去分词之间使用。只适用于肯定句和疑问句。

Just in a sentence:
Just在一个句子中：

I’ve just called my grandmother. (Present Perfect)/Have you just called your grandmother? (Present Perfect)/We had just< finished dinner. (Past Perfect)
我刚给我奶奶打过电话。你刚给你奶奶打过电话吗？我们刚刚吃完饭。（过去完成）

NOTE: In American English just can be used with Simple Past.
注意：在美式英语中，只是可以用简单的过去。

For example,
例子

I just saw him outside./I just called my grandmother.
我刚看见他在外面。/我刚打电话给我奶奶。