YOU MUST BE A LOVELY GIRL.XIXI什么意思

谁帮我解释一下这句话的意思。

You must (be joking). you must (be joking) You must be home at ....? You must be hungry,____? he must be a doctor SO you must be careful ,have a look first ,___you will go the wrong way 请问must be off ,see you是什么意思 You must be can do it you must be home at ten是什么意思 you must be haoopy!什么意思？