They flew their kites on Easter morning.
My question is that why there is "on" instead of in because we use in with the afternoon, morning ,evening.etc.
I am looking forward to seeing you later.
Why "seeing" i.e -ing form of verb is used after looking forward to.
The party comprised of six people.
Why not “of” is used in above sentence
Please comment......
I read in these forums, not lng ago, that there is no rule for every single case of the use of prepositions, and I agree with that. Sometimes, you'll just have to memorise what prepositions go with what words.

1. I don't know why 'on' is used in that sentence. You say, for example, "on Easter Sunday", and that makes sense because we use "on" before the days of the week. I hope someone will post an explanation for "on Easter morning".

2. "look forward to" is a phrasal-prepositional verb, and it is always followed by an -ing verb. "To" is part of the verb (it is not part of the verb that commes after it). It is a preposition, and we use the -ing form for the verbs that follow a preposition.
You can also use a noun after 'look forward to': "We're looking forward to your party on Saturday."

3. Either "The party was comprised of six people."
"The party comprised six people."

'be comprised of' is similar to 'consist of'.

As far as I know we use "on" whith places and time:
on friday
on Christmasday

You can use "in" if you want to point to some range of time
in the evening
in the morning

Wim Alsemgeest
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About "on Easter Sunday":

We use on with special days/dates:

She was born on Valentine’s day.
I have an exam on my birthday.
The Romans began a tradition of exchanging gifts on New Year's Eve. (eve comes from evening, right?)

I think that "Easter morning" can be considered a special day/date, too..

Do you agree, Miriam?
Of course I agree, what else could I do? lol
I'm not the most reliable source when it comes to the use of prepositions in English. And I know I'll never get them right myself... but I keep trying. Emotion: smile

We use these prepositions to talk about time:

{in} + {year/month/season/time of day (except night)}

in 1976

in March

{on} + {day/date}

on Monday

on the 15th of July

{at} + {clock time/night}

at ten o'clock

at midnight

[Taken from http://free-esl.com/students/gg/prepositions/preptime.asp ]

Students: We have free audio pronunciation exercises.
- at noon
- at dusk
- at dawn

- at Christmas
- at Christmastime
- at Easter

I've learned all of the above as sort of 'collocations', but I can't say that I know why these perpositions, and not others, are used in those cases. What is the rule behind them? Or are these examples exceptions to certain rules?
This surely doesn't happen in every aspect of the language, but I have a feeling that, sometimes, the exceptions in the use of prepositions are as many as the items that illustrate the rule. And this makes me wonder: is it possible to actually have a rule, when you find the number of exceptions is so large?

I wouldn't say there is a hard and fast rule which governs the way of using all the prepositions which we use. The context and aspects like AmE or BrE decide the prepositions.

1.He is in the room.

2.He is on the roof top.

In the first one we can think of three dimensional nature but not the second one. Your roof top is just a surface. Usually, three dimensional feature reflects by the preposition 'in'.

Something is on the table but something is in the drawer. Your drawer comes under three diamensional category.

The majority of people who write computer literature, however, write 'on your computer'. I am forece to think my computer screeen is akin to a surface of a table.

We used to say the data is on your computer. We have to accept it.