题干

化学与科学研究、日常生活有着密切联系,下列有关说法正确的是(    )

A:用酒精可以除去水壶中的水垢

B:真假毛线可以通过灼烧的方法进行鉴别

C:三聚氰胺(结构如图)的摩尔质量为l26g

D:八宝粥(含桂圆、红豆、糯米等)不加糖,比加糖还甜,糖尿病人可以放心食用

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答案(点此获取答案解析)

B

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    Every day, a homeowner in Pennsylvania is reminded of a mistake he made 13 years ago. At around 8 in the evening, his peaceful house comes alive with the noise of an alarm clock he dropped into the wall over ten years ago. It's been stuck in the wall ever since.

    13 years ago, Jerry Lynn wanted to make a hole through his living room wall, so he could pass the television cable (电缆)through it. He didn't want to destroy any pipes in the wall, so he came up with a good idea to make sure that he was drilling(钻孔) in an empty place. He took his alarm clock, tied it to a string(线) and set it to go off in 10 minutes. Then he lowered it into the wall, and waited for it to ring. His goal was to drill a hole in a safe place near the place where the ringing was coming from, making sure that there was nothing to pass through there. It all went smoothly until the alarm clock fell into the wall.

The man didn't get back the alarm clock, but thought it would probably run out of battery(电池)in several months, so he wasn't too worried about it. But 13 years later, the alarm clock still rings every day.

    As you can imagine, Jerry and his wife have gotten used to the ringing living room wall, but it can still surprise  guests. So Jerry decides to pull down that wall, just to stop that boring thing, though after putting up with it for 13 years, he think it will be a pity. He says, “I've never herd of a clock battery lasting that long and my friends think it may be interesting to see how long it will keep ringing for.”