题干

用小刀轻轻地把金属钠切下一小块放入盛水的烧杯中,观察到钠与水剧烈反应,并放出热量,钠本身融化成一个闪亮的银白色小球,浮在水面上.根据以上叙述,推断金属钠的性质.

①物理性质:颜色状态____、熔点____、硬度____、密度____②化学性质:____.

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答案(点此获取答案解析)

银白色固体,低,小,比水密度,能与水发生反应

同类题1

阅读理解

老师的眼睛

    ①我永远也忘不了陈老师的那双意见。尽管这双眼睛并不大,也不是“双眼皮”,不相识的人也许会以为这不过是一双挺普通的眼睛罢了。可在我和同学们的心目中,这是世界上最美、最美的眼睛。

    ②许多人说,影星的眼睛很美。可我总觉得她们的眼睛缺少了点什么。而陈老师眼里有的,正是这个。

    ③有一次,我病了,很重,在家躺了一个星期。当我重新坐在课堂上时,那双眼睛总不时地看我几眼。我觉得它仿佛在问我:“身体怎么样,能行吗?”还有一次,我摔坏了腿。陈老师知道了,到家里看我。见我为功课苦恼,就柔声劝慰我别担心功课,安心养好伤,落下的功课她给我补……听着这亲切的话语,望着正在帮我削苹果的老师,我抬起模糊的泪眼,望着那双已经。我觉得陈老师的目光里,有一种软乎乎、甜酥酥的东西包住了我的全身。后来,我终于明白了这就是“爱”啊呀!神圣的爱!是师长对学生炽诚的爱!母亲不也正是这样爱着孩子们吗?我第一次将“母亲”——“老师”这两个词联系起来,觉得那么自然、贴切!

    ④陈老师的眼睛也不总如此。有时竟会那么严厉!有一次测验,她告诉我们最后一道题很难,一定要抓紧时间做前面的。做着做着,我忽然发现有两道应用题在作业上做过。年知怎的,我那不争气的手怎么会放到了作业本上!A可还没等翻开,心就跳得很快,手指也颤得厉害。同时感到有一双严厉的眼睛盯着我,紧紧地盯着我。我一抬头,正与那目光相遇。那目光里充满了责备,B使我的背上像遭了芒刺一般;又像一个正在偷东西的小偷当场被抓住一样惶恐、窘迫、难堪。我的手无力地从作业本上滑落,胆怯地垂下眼睑。我不知自己是怎么交的卷,C只觉得脸上红得厉害,发高烧也未这样难受过。下课了,陈老师问我刚才想什么,我无言辩解,也无法辩解。我偷偷看了陈老师一眼,突然从那目光中看出一种期待,急切的期待。我不敢正视那目光,慌乱地低下头,在那充满期待的目光的注视下,羞愧地,但又是勇敢地承认了错误。陈老师托起我的头,又帮我整好衣领,愉快地说:“这才是个好孩子呢!去把,好好复习功课,祝你下次考好!”我又望了望那双眼睛,那里流露出欣慰与抚爱的笑意。泪水迅速盈满了我的眼眶。含着悔恨与感激交织的泪水,D不知为什么竟会对老师笑了笑,真想对老师说声:“谢谢您!”可不知为什么,又没说出来。

    ⑤每当我想起这件不光彩的事,就脸上发烧;每当我想起陈老师那双美丽的眼睛,就会浑身充满了力量。

    ⑥哦,陈老师的眼睛,所以老师的眼睛,是人类最深邃的,最富有洞察力的眼睛!

同类题2

根据短文理解,选择正确答案。

    Once when I was facing a decision that involved high risk, I went to a friend. He looked at me for a moment, and then wrote a sentence containing the best advice I've ever had: Be bold and brave — and mighty forces will come to your aid.

    Those words made me see clearly that when I had fallen short in the past, it was seldom because I had tried and failed. It was usually because I had let fear of failure stop me from trying at all. On the other hand, whenever I had plunged into deep water, forced by courage or circumstance, I had always been able to swim until I got my feet on the ground again.

    Boldness means a decision to bite off more than you can eat. And there is nothing mysterious about the mighty forces. They are potential powers we possess: energy, skill, sound judgment, creative ideas — even physical strength greater than most of us realize.

    Admittedly, those mighty forces are spiritual ones. But they are more important than physical ones. A college classmate of mine, Tim, was an excellent football player, even though he weighed much less than the average player. “In one game I suddenly found myself confronting a huge player, who had nothing but me between him and our goal line,” said Tim. “I was so frightened that I closed my eyes and desperately threw myself at that guy like a bullet — and stopped him cold.”

    Boldness — a willingness to extend yourself to the extreme—is not one that can be acquired overnight. But it can be taught to children and developed in adults. Confidence builds up. Surely, there will be setbacks (挫折) and disappointments in life; boldness in itself is no guarantee of success. But the person who tries to do something and fails is a lot better off than the person who tries to do nothing and succeeds.

    So, always try to live a little bit beyond your abilities—and you'll find your abilities are greater than you ever dreamed.