（I）求直方图中a的值；

（II）设该市有30万居民，估计全市居民月均用水量不低于3吨的人数并说明理由；

（III）若该市政府希望85%的居民每月用水量不超过标准x吨，估计x的值，并说明理由．

用所给单词的适当形式填空
(1)I love places where the people are really ____  （friend）.
(2) I want to go there, because I like____ （excite）vacations.
(3) Could you please ____ （give）me some____ （suggest）for vacation spots?
(4) Would you like ____  （drink）some orange juice?
(5) You look tired, why not ____  （have）a short rest?
(6) His brother is considering ____  （study）abroad.
(7) Do you plan on____  （stay）overnight here?
(8) Most private cars ____ （not allow）in downtown Singapore.