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问题 填空题

用元素符号或化学式表示

(1) 2个氮原子___________；

(2) 红磷______________；

(3) 5个钠离子__________；

(4) 保持二氧化碳化学性质的最小粒子________ 。

答案

（1）2N  （2）P    （3）5Na+  （4）CO2

题目分析：(1)氮原子用氮的元素符号来表示，元素符号前面的数字表示原子个数，所以2个氮原子表示成2N。

(2) 红磷是固态非金属，其化学式与元素符号相同，用P来表示。类似的除固态非金属外，还有金属、稀有气体。

(3) 离子符号前的数字表示离子个数，又因每个钠离子带1个单位负电荷，所以5个钠离子用5Na+表示。

(4)保持物质化学性质的最小粒子是分子，故保持二氧化碳化学性质的最小粒子是二氧化碳分子，用符号CO2表示。

阅读理解

How would you like to wear the same underwear (内衣裤) for weeks? Owing to the work that has gone into developing intelligent materials, this may not be as   41  as it sounds. Self-cleaning clothes have now been created, and these new materials provide   42  resistance to dirt as well as water. As a result, they require much less cleaning than traditional materials.

The creation of self-cleaning clothes provides an example of how nature helps scientists develop better products. This self-cleaning nature is known as the “lotus effect”. The name comes, of course, from the lotus leaves, which are famous for growing in muddy lakes and rivers while remaining almost   43 

clean. By observing nature, scientists are   44  the qualities of the lotus leaves to the materials they have engineered. Because of this, some remarkable new products have been   45 . Among them are special windows that are resistant to dirt and water. A special   46  on these windows not only prevents dirt from sticking to their surfaces, but also allows dust to be easily washed off by the rain. In fact, these new windows have already been   47  to some cars. Even when traveling at high speed through rain, these cars never have to use their windshield wipers (雨刮器).

Although we have already seen some practical applications, even more dramatic   48  will be made in the future, and they will, perhaps, change our world completely. Undoubtedly, technology is an important development, and it will have an even bigger   49  on our lives.
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单项选择题

この教訓を生かして（）こそ成功させよう。

A.一度

B.二度

C.今度

D.再び
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