用10 mL 0.1 mol·L^－1 BaCl₂溶液恰好可使相同体积的硫酸铁、硫酸锌和硫酸钾三种溶液中的硫酸根离子完全转化为硫酸钡沉淀，则三种硫酸盐溶液的物质的量浓度之比是  (   )

    Hi, I am a Chinese boy (中国男孩). My name is Chen Yang. My first name is Yang. My family name is Chen. My English name is Dale. I like (喜欢) red. My telephone number is 178­4267.I have a good friend. He is English (英国人)．His name is Jim Smith. Jim is his first name and Smith is his last name. His Chinese name is Huang Qiang. His phone number is 362­4597.

As a famous dancer, she needs ____ (dance) for two hours every day.