对于某些离子的检验及结论正确的是

题干

对于某些离子的检验及结论正确的是

A：加盐酸有无色气体产生，该气体能使澄清石灰水变混浊，原溶液中一定有CO₃^2—

B：加氯化钡溶液有白色沉淀产生，再加盐酸，淀淀不消失，原溶液中一定有SO₄²^－

C：加氢氧化钠溶液加热产生的气体使湿润红色石蕊试纸变蓝，原溶液中一定有NH₄^＋

D：加入NaOH后溶液中先产生白色沉淀后又消失，原溶液中一定有Mg²⁺

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C

A

What do they usually do?
John Smith lives in a basketball club. He gets up at five thirty every day. After that, he runs. At eight o'clock, he eats breakfast.	Tom White is a writer. He gets up at eight o'clock in the morning. He usually reads books for two hours after breakfast.
Mary Green is a music teacher. She gets up at six o'clock every morning. Then she eats breakfast. She lives at school but she isn't with her parents.	Mona Black is a clerk. She works at a clothes store. She usually gets up at six thirty. After breakfast she goes to the store by bus.