Why is it correct use have in the present continuous tense when talking about parties but incorrect when talking about class. For example:
I am having a party tomorrow.
I have class tomorrow.
but not
I am having class tomorrow”?
You can use having
with events to indicate that you are organizing, arranging, or otherwise causing an event to be expected to occur on a definite timeframe.
I am having a party.
I am having a family dinner.
I am having a meeting at my home.
but not
I am having a doctor's appointment.
I am having a birthday.
I am having a potential visit by my mother in-law.
In the first three, you could replace having
with holding
or organizing
. In the last three, you could not.
The way to say you have a class would be:
I have a class tomorrow.
You could say the same about a party:
I have a party tomorrow.
However, this means that you are attending a party.
"I am having a party" is an idiomatic way to say that you are hosting a party.
have a class
, andhave class
(informal), are in use, however.