preparatory "it"

[Avril]

a) Was it your birthday yesterday? - No, it wasn’t my birthday yesterday.
b) Was yesterday your birthday? - No, yesterday wasn’t my birthday.

Is there any difference between a) and b)? If not, is the “it” a “preparatory it”?

I read this sentence in a textbook: “Yesterday it was my birthday.” Is it spoken English or just a mistake? “Yesterday was my birthday” is the expression I’d use.
Thank you.

[Rasooljafarinejad]

Hi Avril,

"Yesterday" is a "time adverb" and cannot function as a subject.

[Avril]

In dictionaries "yesterday" ("tomorrow" etc.) is also a noun, so it can function as a subject.

[Yankee]

Hi Avril

You can use either sentence a or sentence b. The meaning is the same.

And you're right: the word "yesterday" can be used either as a noun or as an adverb.
.

[Rasooljafarinejad]

I really didn't know that.
thanks