because, it's because, that's because

quote:

How about 2 and 3?
Are they grammatically correct too?

Hi!

Yes. And they sound quite natural.

Thanks.

Hi Apple,

I don't think I would call any of the sentences "quite" (very) natural. Sentence 1 is by far the best of the lot. However, it would be more common to use 'were' rather than 'had been'.

In everyday conversation, sentences 2 and 3 are unlikely as responses to the question 'Why didn't you buy the cakes?'

.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The use of 'that's because...' would be more likely in this sort of scenario:

Amy (referring to the fact that what Mary brought home a few hours ago did not include cakes):
"Hey, Mary didn't buy the cakes!"

Janet (who knows the reason):
"That's because they were sold out."

.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The use of 'it's because...' would be more likely with this sort of scenario and wording:

Amy (referring to the fact that what Mary brought home a few hours ago did not include cakes):
"I wonder why Mary didn't buy the cakes..."

Janet (who knows why):
"It's because they were sold out."

Thank you, Amy.

I don't understand the difference between "know why" and "know the reason". So, I don't see the difference between the two examples you gave me,
when to use "it's because", and when to use "that's because".

Could you explain it again?

Apple