下列物质属于天然高分子化合物的是 A.聚乙烯 B.合成橡胶 C.油脂 D.纤维素

题型:选择题

问题:

下列物质属于天然高分子化合物的是

A.聚乙烯

B.合成橡胶

C.油脂

D.纤维素

考点:合成有机高分子化合物生活中的其他材料及应用(纳米材料、功能高分子材料等)
题型:选择题

关于苏丹黑B(SB)染色,下述概念不正确的是()

A.苏丹黑显示胞浆中过氧化物酶(POX)成分

B.SB染色结果基本上与POX染色结果相同

C.SB染色较POX染色更为敏感

D.SB染色所需时间明显长于POX染色时间

E.SB染色定位胞浆

题型:选择题

By promoting more even income distribution in a developing country, a lower birth rate will______.

A.be achieved

B.achieve

C.have been achieved

D.be achieving

题型:选择题

下列说法正确的是 [ ]

A.电视广播和移动通信都是利用超声波来传递信息

B.微观粒子按从大到小排列顺序为:原子核、原子、夸克

C.超导体和电磁铁都属于高新技术材料

D.中考实行网上阅卷,条形码扫描器中的光敏二极管使用的是半导体材料

题型:选择题

阅读理解。 

     Along the river banks of the Amazon and the Orinoco there lives a bird that swims before it can fly, flies

like a fat chicken, eats green leaves, has the stomach of a cow and has claws (爪) on its wings when young.

They build their homes about 4.6m above the river, an important feature (特征) for the safety of the young.

It is called the hoatzin.

      In appearance, the birds of both sexes look very much alike with brown on the back and cream and red

on the underside. The head is small, with a large set of feathers on the top, bright red eyes, and blue skin. Its

nearest relatives are the common birds, cuckoos. Its most striking feature, though, is only found in the young.

     Baby hoatzins have a claw on the leading edge of each wing and another at the end of each wing tip. Using

these four claws, together with the beak (喙), they can climb about in the bushes, looking very much like

primitive birds must have done. When the young hoatzins have learned to fly, they lose their claws.

     During the drier months between December and March hoatzins fly about the forest in groups of 20 to 30

birds, but in April, when the rainy season begins, they collect together in smaller living units of two to seven

birds for producing purposes.

1. What is the text mainly about? [ ]

A. Hoatzins in dry and rainy seasons.

B. The relatives and enemies of hoatzins.

C. Primitive birds and hoatzins of the Amazon.

D. The appearance and living habits of hoatzins.

2. Young hoatzins are different from their parents in that _____. [ ]

A. they look like young cuckoos

B. they have claws on the wings

C. they eat a lot like a cow

D. they live on river banks

3. What can we infer about primitive birds from the text? [ ]

A. They had claws to help them climb.

B. They could fly long distances.

C. They had four wings like hoatzins.

D. They had a head with long feathers on the top.

4. Why do hoatzins collect together in smaller groups when the rainy season comes? [ ]

A. To find more food.

B. To protect themselves better.

C. To keep themselves warm.

D. To produce their young.

题型:选择题

商业银行持有的下列资产中流动性最强的是( )。

A.中央银行票据
B.金融债券
C.普通股票
D.企业债券

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