They say here the next sentence is correct with "on the morning that" and incorrect with "in the morning that":
(1a) Why was the old woman so happy on the morning that Peter visited her? — correct
(1b) Why was the old woman so happy in the morning that Peter visited her? — incorrect

As I understand, (1a) & (1b) are subject to the standard rule:
"in the morning" — if there aren't any other words describing the morning,
"on the morning" — if there are other words describing the morning.

They say here the next sentence is correct both with "the afternoon on which" and with "the afternoon in which":
(2a) It was sunny the afternoon on which I saw him. — correct
(2b) It was sunny the afternoon in which I saw him. — correct
But following the standard rule I wrote above, (2b) must be incorrect.
Then why is (2b) correct?
And how do we need to change the rule in order to take (2b) into account?

  • 1
    For what it's worth, I would generally use on for dates and in for times of day, so It happened on the morning of September 27th or It happened on Sept. 27th, in the morning. Oct 27, 2022 at 8:08
  • 2a abd 2b=buzzer. It was sunny on the afternoon I saw him. which is not needed at all.
    – Lambie
    Oct 28, 2022 at 20:35

3 Answers 3


I would not regard the source you quoted as authoritative. In my opinion, both sentences require an additional preposition:

It was sunny in the afternoon on which I saw him.

In addition, the 2b sounds incorrect to me, even with this extra preposition.

That said, grammar came first and then linguists made up 'rules' to explain the grammar. There is no particular requirement for people to stick to these made-up 'rules', especially for as obscure a construction as sentence 2b. The source is from Arkansas, and English usage may be a little different from my British English.

  • I quite agree that this is the reason why OP's example 1b Why was she so happy in the morning that Peter visited her? is "unacceptable". But Why was she so happy in the morning on which Peter visited her? is a bit tortuous, which is why we usually go for OP's version 1a with just a single preposition. Oct 27, 2022 at 12:54

I believe that most English-speakers would say that an event occurs "on" a particular afternoon, not "in" a particular afternoon. Thus, 2b would be incorrect.

However, keep in mind that English speakers show a lot of variety with their use of prepositions. For example, the U.S. band Flaming Lips has a song called "In the Morning of the Magicians". Thus, while "on" is more common for a specified time period (when that time period is a part of a day), "in" is sometimes used, too.


"In the morning" is an idiom that refers to a time period:

She was happy in the morning.

This time period construction says when she was happy. A modifier would need to take the form of "when".

*She was happy in the morning when Peter came to visit."

"On the morning" refers an occasion and actually requires a modifier to indicate the particular morning we're talking about.

She was happy on the morning (which morning?) that Peter came to visit.

Examples 2a and 2b are correct because they both correctly modify "afternoon". 2a refers to the occasion of my seeing him; 2b refers to the fact that I saw him in the period of time between noon and evening.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .