我认为用whose,这里是所有格.out of ...open mouth如果按简单句,那...里填得肯定是“谁的”（one's）open mouth.从句中这种地方填得也应是相应的词,如这里的whose,表示一种所有,拥有,which因此不妥.并且whose在从句中代人代物都可以,所以放心用.这里whose指代的是teapot's.这句话可看成The teapot is just like a chinese duck.the tea is supposed to come out of its mouth.变成从句就如例句.第二句介词词组提前.