在其他条件具备时,若一反应较难进行,则其主要原因可能是( ) ①参加反应的分子的

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问题:

在其他条件具备时,若一反应较难进行,则其主要原因可能是(  )

①参加反应的分子的能量普遍较低

②参加反应的分子的能量普遍较高

③单位时间内反应物活化分子有效碰撞次数较少

④单位时间内反应物活化分子有效碰撞次数较多

⑤反应物分子中活化分子百分数较小 

⑥反应物分子中活化分子百分数较大.

A.①③⑤

B.②④⑥

C.①④⑥

D.②③⑤

考点:影响化学反应速率的因素
题型:选择题

Children’s literature traces its beginnings to preliterate times, when ancient storytellers passed tales and legends from generation to generation in the oral tradition. William Caxton, who established England’s first printing press, published books of etiquette, fables and legends. However, these didn’t constitute a body of work that could be considered literature for children. Because children at that time were considered "miniature adults", books were didactic in nature. The content for young readers consisted mainly of religious instruction, rules of behavior, ethical messages, and moral platitudes. In 1774, Englishman John Newberry changed children’s publishing when he began to create books with attractive formats, quality illustrations, and sturdy bindings, that were designed primarily for children to enjoy. The oldest, and most prestigious award given for children’s books published in America, is the Newberry Medal.
In the following century, children’s literature began to bloom. Hans Christian Andersen’s wonderful stories like "The Ugly Duckling", and "The Little Mermaid", and Grimm brothers collected two volumes of German folktales that included stories such as "Snow White" and "Rumpelstiltskin". Childhood came to be recognized as a joyful and carefree period of life, and books celebrating it began to be published. Charles Dodgson (Lewis Carrol) wrote the fantasy "Alice in Wonderland", the first book that was intended purely for children’s enjoyment without any pretense of instruction. Edwards Lear’s books of nonsense poetry delighted both young and old readers. In North America, books for a young audience were becoming popular as well. Kate Douglas Wiggin wrote "Rebecca of Sunnybrook Farm", Louisa May Alcott wrote "Little Women", and Samuel Clemens (Mark Twain) created Tom Sawyer and Huckleberry Finn. By the end of the century, the pious and moralistic books of earlier times had been replaced by writing designed to amuse and entertain a young audience. In the 1800s color printing was introduced, and by the middle of the 19th century, the rough illustrations that characterized earlier children’s books had been replaced by works of art that captured the word and some of the story.

The word "it" underlined in Paragraph 2 refers to ______.

A.publishing

B.books

C.life

D.childhood

题型:选择题

抗氧剂的作用是减缓加氢汽油含量较多的不饱和烃发生聚合反应生成胶质低聚物。

题型:选择题

浮选是根据矿物表面()性质不同,添加适当药剂,在浮选物中分选矿物的方法。

A、物理

B、化学

C、光学

D、磁电

题型:选择题

このへんは ふゆ( )あたたかい ところです。

A.ので

B.でも

C.では

D.のに 

题型:选择题

请写出废热锅炉(02B001)FDF方式运行成立的条件有哪些?

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