I would say:Hi,
Is this sentence right?
"It is one of her habits to complain all day."
"One of her habits is complaning all day."
If you are talking about the complaining prior to this sentence it can be used, but even then I would say:Thanks, Hockey.
What do you think about sentence 1:
It is one of her habits to complain all day.
Is it natural and do you often use this structure?
Well, this structure will often trip up a native speaker as well, so don't feel alone! Regardless of the structure, the point is made in all the sentences you provided, and in my opinion, one of them can be considered right (the very first one you gave) in the right context. It is also something I often hear from natives in fast, colloquial speech, but I don't think they would ever write a form like that in a novel or a paper.Hockey,
I came across these sentences and I felt strange. I would like to hear your comments.
Thank you, Hockey.