You form this version of the verb by removing the final '-r' of the infinitive and adding "-ndo" which gives:
- "vendendo" from "vender" (to sell)
- "vendo" from "ver" (to see)
- "vindo" from "vir" (to come).
This is one of the few Portuguese rules that doesn't have an exception (well, you do need to remove the accent from "pôr" and its derivatives). Note: "vendo" is also "I sell".
I just found this link in a precedent comment from David.
Qual = Which one Qual + noun = which/what + noun Que + noun = which/what + noun O que = asks for definitions/explanations
So if I undersant correctly, if there is a noun just after, I can use just "Qual": what car is yours? what party are you going? etc. (maybe my English is bad here and I should use "which" in my examples)
But if there is no noun after, I must use "O que": what do you do? What is your name? Etc.
Am I correct or am I oversimplify it? ;)