题干

可以鉴别乙酸溶液、葡萄糖溶液、乙醇溶液的试剂是(      )

A:NaOH溶液

B:新制氢氧化铜悬浊液

C:石蕊试液

D:碳酸钠溶液

上一题 下一题 0.0难度 选择题 更新时间:2018-04-23 11:37:50

答案(点此获取答案解析)

B

同类题1

阅读下面的说明文,完成小题。
                                                                                                       改造火星
        ①我们能把火星变成地球吗?能将火星凛冽寒冷、空气稀薄的地表转化为适宜人类居住的地球环境吗?如果能,我们应该怎样做?
        ②有证据表明,火星形成初期,大量的二氧化碳曾经使火星的气候变得温和,有一段时间曾有河流流入汪洋大海。目前,在火星上仍然可能存在着二氧化碳,在冻结的泥土和极地冰盖中还可能存在着水。
        ③美国宇航局的行星科学家克里斯•麦凯表示,将火星地球化的大部分工作需要火星自身完成。
        ④麦凯说:“人类所做的工作只是将火星的气候变暖,然后撒下孕育生命的种子。”在地球上生活的我们,已经知道让行星变暖的方法,那就是向大气层中添加一些温室气体。全氧化碳是一种强效的温室气体,可以用火星的泥土和空气中的成分合成获得,然后将它释放到大气中。这会使整个行星变暖,接着它们就会释放出冷冻的二氧化碳气体。二氧化碳会促使温度升高,从而将大气压力增加到能让液态水流动的程度。
        ⑤与此同时,威斯康星大学的植物学家詹姆斯•格雷厄姆说,通过这种方法,人类就可以在这颗红色星球上建设一个可持续发展的生态环境。首先在火星的南极地区会生长出细菌和地衣类植物,之后会出现苔藓类植物,一千年或更长时间后会长出红杉树,再经过几千年的时间,长成的森林会逐渐释放出更多的氧气。
        ⑥当前,实现该计划的时间尚待商榷。美国一个由白宫指定的讨论组最近建议首先在月球或小行星上尝试一下,而现在,我们还无法估算出,要将一颗死气沉沉的行星变成地球一样的绿色星球到底需要多少费用。
                                                                                                                                            (选自《科学之友》,有删改)

同类题2

阅读理解

    To develop one's taste in English, the most effective way is to read English books extensively. However, one may be at a loss to choose the suitable books, especially as a beginner. I would like to share some of my experience.

    My first English novel was Jane Austen's Pride and Prejudice, recommended (推荐) by many English teachers and professors as an ideal book for English learners. But I had great difficulty in understanding the novel, let alone enjoying it. It's not the vocabulary that troubled me, but rather the way Austen constructs sentences, and her way of thinking, which seemed too remote to me at that time. My fading enthusiasm was much recovered after reading Hemingway's novel Farewell to Arms. I particularly liked his brief and lively style. So my first suggestion is, as a beginner, you'd better choose contemporary (现代的) novels instead of classical ones.

    However, reading novels is not the only way to improve your English. English essays (散文) can at once inform you, entertain you, and improve your taste in English. The best example is Bertrand Russell's work. Its language is plain, yet you cannot help feeling the elegance and the unique sense of humor. His simple language enables his philosophy (哲理) within the reach of ordinary people. Here comes my second suggestion—essays are indispensable.

    Never follow other's opinions blindly, however famous or influential the person might be. As a saying goes, one man's meat is another man's poison. With that in mind, we are sure to find out our favorite writers through reading and develop our fine taste in English.

同类题5

阅读《一碗馄饨》,完成下列小题。

      ①那天,她跟妈妈又吵架了,一气之下,她转身向外跑去。

      ②她走了很长时间,看到前面有个面摊,这才感到肚子饿了。可是,她______遍了身上的口袋,连一个硬币也没有。

      ③面摊的主人是一个看上去很和蔼的老婆婆,她看到她站在那里,就问:“孩子,你是不是要吃面?”“可是,可是我忘了带钱。”她有些不好意思地回答。“没关系,我请你吃。”

      ④老婆婆端来一碗馄饨和一碟小菜。她满怀感激,刚吃了几口,眼泪就掉了下来,纷纷落在碗里。“你怎么了?”老婆婆关切地问。“我没事,我只是很感激!”她忙擦眼泪,对面摊主人说:“我们不认识,而你却对我这么好。愿意煮馄饨给我吃。可是我妈妈,我跟她吵架,她竟然把我赶出来,还叫我不要再回去!”

      ⑤老婆婆听了,平静地说道:“孩子,你怎么这么想呢?你想想看,我只不过煮了一碗馄饨给你吃,你就这么感激我,那你妈妈煮了十多年的饭给你吃,你怎么不感激她呢?你怎么还要跟她吵架?”

      ⑥女孩愣住了。

      ⑦女孩匆匆吃完了馄饨,开始往家走 去。当她走到家附近时,一下就看到疲惫不堪的母亲正站在路口四处张望……母亲看到她,脸上立即_______出了喜色:“赶快过来吧,饭早就做好了,你再不回来吃,菜都要凉了!”

      ⑧这时,女孩的眼泪又开始掉了下来!

      ⑨有时候,我们会对别人给予的小恩小惠“感激不尽”,却对亲人一辈子的恩情“视而不见”。