【请老师回答,填适当的单词Theboyhasbeenmissingforthreedays.Everyoneisworringabouthis_______(答案填的是safety,我填的是health,不知道根据句意或语法行不行?如果非要填safety,填适当的单词Boysandgirsbeha】

　　请老师回答,

　　填适当的单词Theboyhasbeenmissingforthreedays.Everyoneisworringabouthis_______(答案填的是safety,我填的是health,不知道根据句意或语法行不行?如果非要填safety,

　　填适当的单词Boysandgirsbehave______,becausetheyhavedifferentbehaviors.(为什么填differently,是根据句意吗?填differently,

　　用所给词适当形式填空Moreandmoreteenagersgoabroadfor_______visitsinsummerholidays(education),为什么还有意思