What are some good ways to convince my parents on fostering dogs?

Well first I really live dogs more then anything. I want another dog but my parents won't let me and I know this would be a good way to see if we're ready for another dog. I would buy all the toys and supplies besides the shelter pays for the vet and stuff like that. We have a huge piece of land like 3 acres that is fenced in so the dog couldn't escape. I already trained my dog.(he is a very calm dog one of the calmest in the world he never barks or chases anything he always licks your face and never jumps on anything) and I trained him like that. I also have a cat but she likes all animals. I just need some reasons to tell my parents. I just never had the puppy I wanted and my parents don't understand it. Like I said my dog is awesome but he doesn't fetch or play and when we got him he was already pretty grown. So ya that's basically it thank you for trying to help!!First I haven't actually asked my parents yet so I just need some good reasons to tell them why it is a good idea. And I don't need a puppy I would be fone with a adult dog. My dog just looks so lonely to but my parents just think its my imagination. I would preferably like a puppy but I would be fone with any age dog even an old one.

So what if your parents own a lot of land. That means nothingSo what if you never had a puppy, that doenst make you entitled to one. You just want one so you can play with it and becouse you are bored of the dog you have Their house, their rules, they said no. Respect that and stop asking to 'foster' a puppy just becouse you are bored of your old dog