—Could you tell me_ it's polite to eat noisily in Japan, Kumiko?
—Sure! It's polite to do that. It means you like the food very much.
A：if
B：where
C：how
牛肉面是全省人民“舌尖上的美食”．端上一碗牛肉面，香味扑鼻而来，是由于分子的____造成的；端碗时很烫手，是通过____方式增加了手的内能．
