根据首字母及汉语提示，完成下列单词的拼写，使句意明确，语言通顺。
What do you like to do in your f______(空闲的) time?
I could hear her sweet v______ (噪音) from the next room.
Travelling by plane is expensive, but it s______ (节省) time.
Would you please make a shopping l________ (清单) for the picnic?
It's polite to k______ (敲) on the door before entering a room.