Resolved questions
why "بعضی" can be added by "ها"?

Hi ali,
You need to know بعضی means "SOME" so here because you are talking about people this word means " Some People". You are talking about more than one person so you have added ها to the end of the word بعضی . Look at some more examples:

بعضی ها کار می کنند. Some people are working.
کتاب ها را به او دادم. I gave her the books.
بچه ها بازی کردند. The children were playing.

So ها is the Plural sign in Farsi. In normal speaking people shorten it to ا as below:

دختر ها --> دخترا
کتابها --> کتابا
But we have one more Plurality sign which is ان which is really formal and it mostly applied to animated objects. Look at the examples below:

درختان این باغ سبز و بلندند. The trees in this garden are green and tall.
زنانِ ایرانی همچون مردان کار می کنند. The Iranian women are working just like the men.

درخت + ان --> درختان = tree + s = trees
زن + ان --> زنان = woman + plurality --> women
مرد + آن --> مردان man + plurality --> men

Hope this will help you.

موفق باشی
H.