(2分)今年中央电视台3.15晚会报道,常州广州等地一些液化气充气站在液化气中填

题型:计算题

问题:

(2分)今年中央电视台3.15晚会报道,常州广州等地一些液化气充气站在液化气中填充二甲醚(化学式为C2H6O),有的含量竟高达61.3%.

二甲醚是一种化工原料,对液化气罐的配件有较强腐蚀作用,易造成气罐漏气,严重会引起爆炸.

请阅读信息后,回答:

(1)二甲醚的相对分子质量是                 ;

(2)二甲醚中碳氢氧三种元素的质量比为                       .

考点:物质组成元素的质量比化学式的写法和意义物质组成元素的质量分数化合价的求法
题型:计算题

《孟子》云:“不违农时,谷不可胜食也”;“斧斤以时入山林,材木不可胜用也”。这表明 [ ]

A.自然界的变化是有规律的

B.改造世界必须遵循客观规律

C.自然界的发展规律是客观的

D.客观规律是可以被认识和改造的

题型:计算题

有关细胞因子的共性,正确的是()

A.绝大多数是高分子量的蛋白质

B.多数细胞因子以单体的形式存在

C.细胞因子通常以特异的方式发挥作用

D.细胞因子的分泌不具有自限性

E.细胞因子作用受MHC限制

题型:计算题

阅读理解。

     It's perfectly normal for young children to suddenly decide they hate everything-even foods they loved

yesterday. It's also common for them to go on what experts call food jags-that is, they want to eat the same

few foods over and over again at every meal, while turning up their noses at anything new. "It's a fear of new

things," says Nancy, Hudson, a researcher in University of California, Berkeley. "We think it's one of those

quirks (怪癖) that humans probably developed to protect themselves as mankind came into this world. You

don't try new things because you don't know if they're safe." Children like familiar things, whether they're their

beds or their aftemoon tea,so most kids won't try new foods until they've been shown to them many times.

     Picky (挑剔的) eating can also be a child's way of showing his independence. This is why forcing a child

to eat often makes things worse. Finally, it may seem like your child cannot sit still long enough to eat very

much at one sitting because of his short attention. But children are generally good at getting what they need,

even if it doesn't seem like much to you. In any case, you can try to keep your child at the table longer by

making mealtime as calm and regular as possible, without too many distractions (分心的事物) like toys, TV,

or pets.

1. How many reasons does the writer mention in this passage to explain why children are mostly picky eaters?

A. Three.

B. Two.

C. Four.

D. One.

2. What does the phrase "turning up their noses" underlined in Paragraph l mean?

A. Accepting.

B. Disliking.

C. Putting their noses on.

D. Fearing.

3. Which statement is TRUE according to the passage?

A. Only children like things which they are familiar with.

B. Toys are not good for children.

C. It seems that children like eating more when they have something they like in their hands.

D. Make it a rule to let your child eat at the table when meal- time comes.

4. According to the writer, one of the ways to have children eat new foods is _____.

A. telling them stories while they're eating

B. not giving them any food until they're very hungry

C. letting them become familiar with the new foods

D. explaining to them how useful the new foods are

题型:计算题

网上证的实现是指()

A.将各个网上证的功能利用软件进行设计

B.将各个网上证的内容和功能进行调试和发布

C.用选定的图片设计语言和工具实现各个网上证

D.用选定的网页设计语言和工具实现各个网上证

题型:计算题

下列疾病中出现的胸水不属于渗出液的是()

A.结核性胸膜炎

B.脓胸

C.肺癌

D.心力衰竭

E.胸膜肿瘤

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