英文信中落款为什么用yours mom而不用your mom?

That book is yours为什么用yours不用your, FUCK YOUR MOM 还有 I fuck your mom. How your mom fark your mom 意思 i tell my mom （　　）story为什么用the whole story 不用all the story how is your mom?开头为什么要用how提问呢 Dear mom,mom用大写吗? This invitation is for your mom,对your mom提问 How -----your mom ------- fruit salad Mom,hold on your hats. Your mom是第几人称