i just called the store and the guy who works there really got me confused .
the problem that my camera haven`t arrive yet and they are out of stock so they have to order for me so in that case i can`t try neither of those lenses,what he said :
35mm f/1.8 is a DX lens therefore it`ll give me exact 35mm on my DX dslr ( d7000) .
while the 28mm f/2.8 is an FX lens which means it`ll give me ( 28*1.5=42mm) on my d7000.
so the 35mm f1.8 lens will give me a wider angel than the 28mm D lens on my DX body ?
i thought all kind of lenses will give a multiplied focal length , like my 50mm f1.8 D is giving me 75mm on my d7000
also my previous 18-105mm lens , at 18mm it`s like 27mm so
the 35mm f1.8 lens on a DX body is like 52.5mm or 35mm