on or not , please help me.

is this sentence right?

  1. “My birthday is 20th October 1990” or “My birthday is on 20th October 1990”

Both forms are used.

is this sentence right?[color=blue] I don’t think so.

  1. “My birthday is 20th October, 1990” or “My birthday is on 20th October, 1990”
    a) My date of birth is 20(th) October, 1990. You have only one date of birth, but you have a ‘birthday’ once a year.
    b) My birthday is October 20(th). There is no good reason to add “on”. Your birthday is a (day)(date); it is not on anything.

Having said that, I don’t doubt that many people might add “on”, but I see no good reason to do so. In fact, to me adding “on” is a flaw.

It’s rather pedantic, but with the addition of the year of birth, I accept what you say about ‘date of birth’ being correct rather than ‘birthday’. However in the UK, at least, the addition of ‘on’ is perfectly acceptable and certainly not a flaw.
The birthday is ON that date.

[color=blue] I would say ‘…that day.’
[color=blue]Even if it’s not a flaw, it’s certainly not a merit either. So why use an at least unnecessary word?
I am not telling you or others what to say, but I have expressed my opinion mainly to the original poster.

It’s not unnecessary - the birthday is ON that date.

Day doesn’t work - that would just be… well, the day.

[color=blue]I cannot do it next Friday; my father’s birthday is that day.
[color=blue]What day is your birthday?
My birthday is the same day as yours.

My birthday is (on) February 29(th), so three out of every four years I celebrate my birthday on March 1(st).
The “on” in brackets is clearly not necessary, but the underlined one is. Do you see the difference?

As I have already stated, the addition of ‘on’ is perfectly acceptable and not ‘flawed’.
There is no point in continuing the debate.

In my view, ‘on’ here means ‘falls on’, so it is not incorrect. What do you say, Canadian?

[color=blue]My point is that the “on” we are talking about is totally unnecessary. And “falls on” also has two words replacing “is”.
Using totally unnecessary words can certainly be considered to be a flaw. But I am not saying that unneeded words will always make the sentence’s unclear or wrong. But it can degrade the sentence; using unnecessary words certainly doesn’t improve a (basic English) sentence.
The original poster asked if “on” should be used or not in (his)(her) context, and I gave my answer.
My last post illustrated an example of a necessary “on” related to birthdays.
But the other poster on this thread refuses to see any difference between between the two "on"s.

There is also a larger issue here. English learners very commonly use too many words in their sentences. And that is not surprising, as their English is not yet good enough to write very efficient sentences. This post is a small example of the use of unnecessary words.
And again remember that the original poster asked if that “on” is necessary or not.

Really? Where?

[color=blue]Don’t be silly! The OP asked which one should be used. That’s what “or” means.

Yes, I agree with you, but I would say ‘on’ is not necessary (rather than unnecessary), as it is not incorrect. And, the use of on is well illustrated.

Again, where?
On my screen the original question shows up as ‘is this sentence right?’
Despite the ‘or’ (which links alternatives rather than asks, 'which one should be used) there are plenty of examples on these webpages alone which indicate that it’s perfectly possible to answer ‘both sentences are correct’ - which, your personal prejudices aside, is the correct answer.

Yes, you are right; it is a short question: [b]on or not/b, but has triggered a long debate.

Actually, if you read the first message, you’ll see that he isn’t.

I don’t agree that ‘unnecessary’ is the correct word to describe the concept you are trying to get across. I mean there are so many ‘unnecessary’ words in the English language and we still use them. Here is just an example: ‘My name is Mike’. The word ‘is’ is totally unnecessary, the meaning of the sentence is perfectly clear without ‘is’. If you translate the same sentence from Russian into English word by word you get exactly this: ‘My name Mike’ and to Russian ears this sounds perfectly fine. However, native speakers would correct any Russian speaking like that. So, it’s not always people learning English as a second language who are using too many (‘unnecessary’) words. Let’s take another look at prepositions of time. You can say: ‘Let’s meet Monday’ or ‘let’s meet weekend’. Does it sound good? No. Will you be understood? Probably yes. Or what about the articles? Are they really always ‘necessary’? Here is example. I can say: “This shouldn’t happen again in future”. In the UK ‘in future’ is a perfectly acceptable phrase while Americans will probably frown upon it because they prefer ‘in the future’. But while we are at it, why not just say ‘this shouldn’t happen again future’. Is the ‘in’ really ‘necessary’?

TOEIC listening, photographs: The musicians

Just to let you know, “Let’s meet Monday.” is fine, but “Let’s meet weekend.” is not.

I know but it’s not a question of words being unnecessary or not. The preposition is unnecessary in both sentences.[YSaerTTEW443543]

TOEIC listening, photographs: Construction in progress[YSaerTTEW443543]

Frankly, Luschen, I would say these two sentences will be treated as unacceptable without suitable prepositions. Most of us would say: Let’s meet on Monday. "Let’s meet at this (the) weekend. These prepositions are not necessary, though.