一、单项填空（共15小题，每小题1分，满分15分）从A、B、C、D四个选项中，选出可以填入空白处的最佳选项．
1．The temperature is usually _____ 30℃most of the days in summer in Nanjing．（ ）
A．above B．below C．over D．under
2．﹣Mum，where should I put the plastic and paper？
﹣I think you'd better separate _____ into different groups first．（ ）
A．they B．them C．their D．theirs
3．﹣__________ I see your ID card？We have to check your personal information．
