I don't know ___the price of the book is.A how much B how many C what mach D what

I really don't know how to ___the problem?(处理) I don't know when I can post the letter.改为同义句I don't know ___ ___ ___the letter.请问这是什么句型?为什么这么填? I don't know. “i don't know you know i don't know sorry,I don't know. i don`t know much I don't really know. 英语；I don't know I don't know miss I don't know him. I don't know now 翻译 i don't know So know,I don't I don't know her i don't know anything 英语翻译I don't know___ ___ ___the work tomorrow I know enough to know that I don't know I don't know ___the price of the book is.A how much B how many C what mach D what