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    Betty has travelled to Beijing several times since 1980, and this is how she has seen the city change.

The Great Wall

Then

Visiting the Great Wall at Badaling on my first trip, I ran into only a few tourists from local Chinese tour buses. Years later, to avoid the crowds at Badaling, I went to the Great Wall at Mutianyu. My six-year-old son was so excited that he said, “Every step is enjoyable!”

Now

Most tourists still see the Great Wall at Badaling, but a great many come to Mutianyu now. Many hikers like to visit the Great Wall at Jiankou for the beautiful sights. There are no cable cars (缆车) and often even no steps.

Shopping

Then

In the 1980s, tourists used foreign exchange certificates and the Chinese people used renminbi. Credit cards (信用卡) were not widely used.

We visited the Beijing Department Store (opened in 1955). And it was on the street, Wangfujing. Everything in it was very cheap and made in China.

Now

People can pay in many new ways such as Alipay (支付宝) and Wechat Pay. Also, credit cards are accepted almost everywhere.

Now Wangfujing is a famous street where people can buy all kinds of things. The Beijing Department Store is still there. Goods are cheap. The store is bigger now.

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同类题5

氮的固定是几百年来科学家一直研究的课题.

(1)如表列举了不同温度下大气固氮和工业固氮的部分K值.

反应

大气固氮

N2(g)+O2(g)⇌2NO(g)

工业固氮

N2(g)+3H2(g)⇌2NH3(g)

温度/℃

27

2000

25

400

450

K

3.84×1031

0.1

5×108

0.507

0.152

①分析数据可知:大气固氮反应属于____ (填“吸热”或“放热”)反应.

②分析数据可知:人类不适合大规模模拟大气固氮的原因 ____ .

③从平衡视角考虑,工业固氮应该选择常温条件,但实际工业生产却选择500℃左右的高温,解释其原因____ .

(2)工业固氮反应中,在其他条件相同时,分别测定N2的平衡转化率在不同压强(р1、р2)下随温度变化的曲线,如图所示的图示中,正确的是 ____  (填“A”或“B”);比较р1、р2的大小关系____ .

(3)20世纪末,科学家采用高质子导电性的SCY陶瓷(能传递H+)为介质,用吸附在它内外表面上的金属钯多晶薄膜做电极,实现高温常压下的电化学合成氨,提高了反应物的转化率,其实验简图如C所示,阴极的电极反应式是 ____ .

(4)近年,又有科学家提出在常温、常压、催化剂等条件下合成氨气的新思路,反应原理为:2N2(g)+6H2O(1)⇌4NH3(g)+3O2(g),则其反应热△H=____ .

(已知:N2(g)+3H2(g)⇌2NH3(g)△H=﹣92.4kJ•mol1,2H2(g)+O2(g)⇌2H2O(l)△H=﹣571.6kJ•mol1