下列说法正确的是{"A":"\u707c\u70e7\u67d0\u767d\u8272\u7c89\u672b\uff0c\u706b\u7130\u5448\u9ec4\u8272\uff0c\u8bc1\u66

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下列说法正确的是（）

A：灼烧某白色粉末，火焰呈黄色，证明原粉末中含有Na⁺，无K⁺

B：实验中要配制500mL0.2mol•L^﹣1KCl溶液，需用托盘天平称量7.45gKCl固体

C：加热盛有NH₄Cl固体的试管，试管底部固体消失，试管口有晶体凝结，证明NH₄Cl固体易升华

D：做蒸馏实验时，在蒸馏烧瓶中应加入沸石，以防暴沸．如果在沸腾前发现忘记加沸石，应立即停止加热，冷却后补加沸石

上一题下一题 0.0难度选择题更新时间:2020-01-11 12:00:18

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D

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阅读下面短文，掌握大意，从A、B、C、D四个选项中选出最佳选项。

Dear Mum and Dad,

How are you? I'm happy 1 America. It's cool here. What is the 2 like in London? Uncle Bob and Aunt Jenny are nice to 3. This is Uncle Bob and Aunt Jenny's 4, Toby. He is thirteen years old. We are good friends now. We 5 basketball every day. Tomorrow 6 Saturday. Uncle Bob and Aunt Jenny want to take Toby and me to the Haines Shoe House. It is a 7. It is 67 years old. Here is a 8 of it. There are two bedrooms, one kitchen 9 one living room. There is an ice cream shop in it too. I love ice cream! Are there 10 computers or TVs in the hotel? I will find it out (查明) tomorrow.

测定时间	8：05	8：10	8：15	8：20	8：25	8：30
pH	4.94	4.92	4.90	4.88	4.86	4.85

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