根据括号中所给的汉语写出单词，使句子意思完整正确。
—How often do you have a sports meeting in your school, Millie?
—________(一次)a year.
We are ________ (幸运的) enough to get so many tickets to Forest Park.
It is necessary for everyone to know the ________(重要性) of protecting wetlands.
We should wait for our turns to get on the bus      (礼貌地)．
Mr Yang said he ________(更喜欢) reading a book to reading an e-book on the Internet.