Just - As a Time Expression
1.Just = Recently
Just is most often used to express that something has recently happened.
Use just with the present perfect tense to indicate that an action has recently occurred and influences the present moment of speaking.
I've just been to the bank.
Tom's just arrived. You can speak to him now.
Mary's just finished the report.
Exception: American English vs. British English
In everyday conversation American English uses just with the past simple, as well as the present perfect, to express that something recently happened. In British English, the present perfect is used.
He just finished lunch.
He's just finished lunch.
Jane's just been to the bank.
Jane just went to the bank.
2.Just = Immediately
Just can also be used as a time expression to mean that something important will happen immediately. In this case, use the present continuous tense or 'going to' to express that something is about to happen.
He's just getting ready to go now.
I'm just going to finish this and then we can go.
3.just = Close to the Time
Just is also used to express that something happened at approximately to the time mentioned in phrases such as: just after, just before, just when, just as.
just也可以用于表示某事发生的时间接近于短语中提到的时间，例如just after、just before、just when、just as等。
I saw Tom just as he was leaving yesterday.
Jennifer finished the report just as the boss asked her for it.
Just when you think you've seen everything, something like this happens!
4.Just - as an Adverb Meaning 'Only'
Just is also used as an adverb meaning 'only', 'merely', 'simply', and so on.
Don't worry about that cup, it's just an old thing.
She said she just needed some vacation time to relax.
Richard is just the spokesman.
5.Just - as an Adverb Meaning 'Exactly'
Just can also be used as an adverb meaning 'exactly' or 'precisely'.
That's just the information I need to understand the situation.
Alexander is just the person for the job.
6.Just - as an Adjective Meaning 'Honest'
Just is also used as an adjective to mean that someone is honest, or fair in his judgement.
He's a just man so you can expect to be treated well.
You need to be just with all your students, not just the ones you like.
Fixed Expressions with 'Just'
Just is also used in a number of idiomatic and fixed expressions. Here are some of the most common:
Just in time = Ready at the exact moment necessary
In the business world many products are made 'just in time'. In other words, they are ready when a customer needs them and not before.
Our supplier uses just in time manufacturing to fill our orders.
Using a just in time approach reduces our warehousing costs by 60%.
1.Just off the boat = Naive, not experienced
Someone who is 'just off the boat' is new to a situation and doesn't understand certain unwritten rules, or ways of behavior.
用just off the boat来形容某人，意义则是初来乍到，不懂得一些不成文的规矩或行为方式。
Give him some time to adjust to the new position. Remember he's just off the boat and will need some time to get up to speed.
They seemed as if they were just off the boat because they couldn't understand what was being asked of them.
2.Just the ticket = Exactly what is needed
'Just' is used like 'exactly' when expressing something that is precisely what is needed in a situation.
The two weeks off work was just the ticket. I feel like a new man.
I think your ideas are just the ticket for our marketing campaign.
3.Just what the doctor ordered = Exactly what is needed
'Just what the doctor ordered' is another idiomatic expression that expresses the idea that something precisely what is needed in a situation.
Just what the doctor ordered是另一个习语表达，意思是在某种情形下，某物刚好被需要。
I think his solution was just what the doctor ordered.
The grammar review was just what the doctor ordered for getting students ready.