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Mandy:Hello, Jessica. Long time no see.Jessica:Hi, Mandy. Wow, you look great! Have you changed something about yourself?Mandy:(1)_.Jessica:Nice. Can you tell me which one?Mandy:The one over on Oak Street.Jessica:(2)Mandy:Let me see… I got a manicure, a pedicure and a facial. Then I had a massage and dyed my hair.Jessica:Sounds expensive.Mandy:(3)__Jessica:Hey… What are you doing?Mandy:I'm taking a selfie (自拍). I want to post it to Facebook and show everyone the "new" me.Jessica:Cool! You look awesome!

NaCl、NaBr、MgO和BaO四种晶体中离子键从强到弱的顺序为:

A. NaCl>NaBr>MgO>BaO
B. NaBr>MgO>BaO>NaCl
C. MgO>BaO>NaCl>NaBr
D. BaO>MgO>NaCl>NaBr

下列关于离子键的说法正确地是:

A. 当两种元素电负性差值>1.7时,形成的化学键倾向于离子键
B. 离子晶体中的离子键就是一个正离子和一个负离子之间的静电引力
C. 离子键键能的大小与离子半径、离子电荷有关
D. 离子键具有饱和性和方向性