Q: My 17 month old says "No" to everything and is adamant about it. Any thoughts on getting more "yes's" and "mams" or "sirs"? Is this a phase?
A: 17 months old is too young to expect polite manners. Your daughter is still exploring speech and language, and socially, she isn't yet at the point where she is capable of following social "rules". It's best to let her experiment with speech. Praise her and engage with her when she "speaks nicely", and ignore the rude or annoying things she says. Her language development is in a period that we call "the language explosion", and it's important that she get all the encouragement and support that she can, to maximize her development. Have fun with it!