⑴five  ____                                 A.

⑵six ____                                    B.

⑶one and three  ____                  C.

⑷fifteen ____                               D.

⑸sixteen ____                               E.

现有 0.175 mol•L^﹣1醋酸钠溶液500 mL（室温下，醋酸的电离平衡常数K_a=1.75×10^﹣5）．

— No, I don't. It's _______ for me.

香港、澳门人多地少，为了城市的扩展，它们都采取的措施是（   ）