It shouldn't be two sentences.
I wanted to ask my friend to complete my work but he did it before I asked him.
I wanted to ask my friend to complete my work but he did it before I could ask him.
I wanted to ask my friend to complete my work but he did it before I had a chance to ask him.
I wanted to ask my friend to complete my work but he did it without my asking.
My friend would have asked me to [STRIKE]get[/STRIKE] do his work [STRIKE]done[/STRIKE] but I [STRIKE]got[/STRIKE] did it [STRIKE]done[/STRIKE] without him/his asking. Is this sentence correct?