On a holiday, people __________ work.[ ]
A. isn't
B. aren't
C. don't
答案：C
下列关于物质性质变化的比较, 不正确的是 ( )
A．酸性强弱: HIO4<HBrO4<HClO4
B．原子半径大小: Na > S > O
C．碱性强弱: KOH > NaOH > LiOH
D．还原性强弱: F- > Cl- > I-
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