Singular or plural

Agreement is between the subject and the verb.

Equative sentences like these put the subject before the verb, the same as with almost all sentences.

So long sentences, being plural, has to agree with the plural verb are.

Long sentences are my thing.

My thing is long sentences.

CJ

what about

flirting with women is my thing.
or
flirting with women are my thing.

I mean like. It's only one of these things that specifies me. if you understand what I mean?

Like Paul's thing is collecting coins.
Sandra's thing is typing long sentences.
and so on.

would it still be as you explained it then?

I might be explaining very poo

Flirting with women is my thing.

The gerund is singular. Your thing is one type of activity.

That is what I meant with my example, with "long sentences" too. it's "my thing". this is what I do. I type long sentences.

wouldn't it be "long sentences is my thing" then?

Supposing you were preparing a manuscript for publication in a journal, I believe an editor would insist on a change from Long sentences is my thing to Long sentences are my thing unless he could convince you to write this instead:

Typing long sentences is my thing.

(He might also point out, as an aside, that neither sentence is long enough to demonstrate its

Hehe. Okay then. So we were both right then I guess.
The point was towards the thing that's specific for someone anyway.

Thanks everyone for the answers.

So we were both right then I guess.

Sadly true for most debates and disagreements.