题干

某同学选择韭黄进行色素的提取和分离试验,下列叙述正确的是

A:可以用蒸馏水代替丙酮提取色素

B:色素提取液没有颜色

C:分离色素不能采用纸层析法

D:层析后的滤纸条上仍有色素带

上一题 下一题 0.0难度 选择题 更新时间:2019-01-09 11:20:38

答案(点此获取答案解析)

D

同类题1

阅读下面短文,掌握其大意,然后从各题所给的四个选项(A、B、C和D)中,选出最佳选项。

    I often read of incidents of misunderstanding or conflict. I'm left1.Why do these people create mistrust and problems, especially with those from other2?

    I was growing up in Kuala Lumpur in the early 1960s,3children from different races and religions played and studied4in harmony. At that time my family lived a stone's5from Ismail's. And no one was bothered that Ismail was a Malay Muslim and I was an Indian Hindu-we just6our differences. Perhaps, our elders had not filled our heads with unnecessary advice, well7or otherwise.

    We were nine when we became friends. During the school holidays, we'd8the countryside on our bicycles, hoping to9the unexpected. At times Ismail would accompany my family as we made a rare shopping trip to town. We would be glad of his10.

    When I was twelve, my family moved to Johor. Ismail's family later returned to their village, and I11touch with him.

    One spring afternoon in 1983, I stopped a taxi in Kuala Lumpur. I12my destination. The driver acknowledged my13but did not move off. Instead, he looked14at me. “Raddar?”he said, using my childhood nickname(绰号). I was astonished at being so15addressed(称呼). Unexpectedly! It was Ismail! Even after two16we still recognized each other. Grasping his shoulder, I felt a true affection, something17to describe.

    If we can allow our children to be18without prejudice, they'll build friendships with people, regardless of race or religion, who will be19their side through thick and thin. On such friendships are societies build and20we can truly be, as William Shakespeare once wrote, “we happy few, we band of brothers”.

同类题5

阅读文本选段,完成小题。

    鸿蒙以后多少年,只有善于攀援的金丝猴来游。以后又多少年,才有人来到这里。第一个来者黄帝,一来到,黄山命了名。他和浮丘公、容成子上山采药。传说他在三大主峰之一,海拔1840米的光明顶之旁的炼丹峰上,飞升了。

    又几千年,无人攀登这不可攀登的黄山。直到盛唐开元天宝年间,才有个诗人来到。即使在猿猴愁攀登的地方,这位诗人也不愁。在他足下,险阻山道阻不住他。他是李白。他逸兴横飞,登上了海拔1860米的莲花峰,黄山最高峰的绝顶。有诗为证:“丹崖夹石柱,菡萏金芙蓉,伊昔升绝顶,下窥天目松。”李白在想像中看见,浮丘公引来了王子乔,“吹笙舞松风”。他还想“乘桥蹑彩虹”,又想“遗形入无穷”,可见他游兴之浓。

    又数百年,宋代有一位吴龙翰,“上丹崖万仞之巅,夜宿莲花峰顶。霜月洗空,一碧万里。”看来那时候只能这样,白天登山,当天回不去。得在山顶露宿,也是一种享乐。

    可是这以后,元明清数百年内,极大多数旅行家都没有能登上莲花峰顶。汪瓘以“从者七人,二僧与俱”,组成一支浩浩荡荡的登山队,“一仆前持斧斤,剪伐丛莽,一仆鸣金继之,二三人肩糗执剑戟以随”。他们只到了半山寺,狼狈不堪,临峰翘望,败兴而归。只有少数人到达了光明顶。登莲花峰顶的更少了。而三大主峰之中的天都峰,海拔只有1810米,却最险峻,从来没有人上去过。那时有一批诗人,结盟于天都峰下,称天都社。诗倒是写了不少,可登了上去的,没有一个。

    登天都,有记载的,仅后来的普门法师、云水僧、李匡台、方夜和徐霞客。