When to use 准时，按时, 准点, 及时？

[songwen]

I am a bit confused as to when to use which word. I can generally understand the meaning when I hear them in a sentence but if I try to make my own sentences I'm not sure which to use.

 

If anyone can give some example where one word can substitute for another AND change the meaning, I think I would get a better idea.

 

Thanks you.

[Guest123]

准时 and 按时 are synonyms, but 准时 is more precise: if you must come at 2:15 PM, you come at 2:15PM, not before, not after. It's called 准时。 You can also use 按时 in this context. But usualy it is more approximate, for ex., if you must come at 2 PM and you come a few minutes before or even one o two minutes after 2PM, you still in time - 按时 。It's closer to 及时 which means in time for someting. It doesn't necessarily mean some hour or date. It can si,mply mean at the right moment. for ex., in some urgent situation when you needed help, a friend came in time when it was not too late to rescue you. 及时赶到

准点 is quite a specific, technical term used, for ex., when talking about flights being on schedule.

[songwen]

Thanks Edita

[Daniel Tsui44]

准 here means "standard". 准时 means "it's the time that appointed." It's used to describe the state of on time. 

按 here means "according to" 按时 means "do things according to the appointed time". 

他很准时。(He is right on time.) here you cannot use "按时"

他准时睡觉。他睡觉准时。The time he goes to bed is the same every day.

他按时睡觉。他睡觉按时。He goes to bed sticking to the bedding time.

准时完成工作。Finish the job on time.

按时完成工作。Finish the job according to the timetable.

他的工作完成的很准时。(His job is finished right on time.) here you cannot use "按时" 

 

 

[songwen]

Thanks for all the replies. I have a good understanding of the differences now!