Here comes the/a bus with a lot of people on it

Hi,

Here comes a/the bus with a lot of people on it and no room for us to get on.

Is this idiomatic? Do you think both 'the' and 'a' articles make sense?

Thanks in advance.

Both are idiomatic and both make sense. Somebody might argue that the usual distinction between definite and indefinite articles applies, but really you could use either and nobody would notice any difference.

Thank you, Probus.

Could you please be kind enough to answer one more question of mine?

I had the/a father who was suffering from dementia.

I guess 'the father' would be idiomatic.

Thanks in advance.

Nope.

A fluent speaker would never say "I had the father". It must be "I had a father".

It would have been much better to start a new thread for this question, with an appropriate title. That way, all readers can learn.

Also, there's no need to post a reply thanking me. If you like my reply just click on the like button.

Cheers:-D

My father suffered from dementia would be more natural to me. Probus is right about which article, but it's not a good sentence IMO.