问题 写作题

第二节:书面表达(满分25分)

请根据右图表提示,以 “ Air pollution ” 为题,分析造成某城市空气污染的原因,并就如何解决这一问题提出一两条可行性建议。

注意:

1. 词数要求:120左右,开头已写好,不计入总词数。

2. 参考词汇:车辆—vehicle,有毒的—poisonous,因素—factor

Air pollution

With the development of industry, air pollution is getting more and more serious.                       

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答案

One possible version

Air pollution

With the development of industry, air pollution is getting more and more serious. In this city, many people suffer from different kinds of illness because of air pollution.

What is the air pollution caused by ? About half of the problem is caused by vehicles. There are more and more cars and buses on the roads every day, which give off poisonous gases. About 30% of air pollution is caused by factories. Another factor is smoking. Smoking does harm to others’ health as well as to that of the smokers themselves. About 10% of air pollution is caused by others.

We must take measures to fight against this pollution. New fuel can be used to replace gas. We can plant more tress. If everybody realizes the importance of the environment and does something to stop pollution, the problem will be greatly reduced. (129 words )

单项选择题
填空题

胃酸过多是常见的胃病。下面是甲、乙两种常见胃药的说明摘要。

甲:①白色结晶状粉末,受热可缓缓分解;

②能溶于水,水溶液呈弱碱性;灼烧时火焰为黄色;

③遇酸及酸性药物则产生二氧化碳;

④患者服用过量,可能引起胃胀气,甚至有引起胃溃疡穿孔的危险。

乙:①与胃酸是中和作用缓慢而持久,可维持3~4小时;

②凝胶本身覆盖于溃疡面上,具有保护作用;

③可溶于稀酸或氢氧化钠溶液中。

(1)请你推测,甲中含有的主要化学成份是____________(填化学式);乙中含有的主要化学成份是

____________(填化学式)。

(2)试写出甲中含有的主要化学成份引起胃胀气反应的离子方程式:____________________________。

(3)三硅酸镁Mg2Si3O8·nH2O也是常用胃药,被用来治疗胃溃疡,是因为该物质不溶于水,服用后中和胃酸作用持久。把三硅酸镁改写成氧化物形式为:_________________________。写出它中和胃酸(胃酸的主要成分是HCl)的化学方程式_______________________________。

(4)目前一种新型抗酸剂能迅速改善和缓解胃酸过多的症状,它主要由碳酸镁、氢氧化镁和氢氧化铝组成(说明:Mg(OH)2在高温下分解为MgO)。现按如下步骤测定药剂中三种主要成分的配比:

①取药剂样品,研磨后,加入50mL3.6 mol·L-1盐酸,正好完全反应并收集得到标准状况下224mL气体

②过滤,弃去其中不溶性物质(其余成分不参与反应)

③取②中滤液,加入足量的NaOH溶液后,过滤、洗涤、灼烧,所得固体2.4g。

则该药剂中三种主要成分的物质的量之比为n(MgCO3):n(Mg(OH)2):n(Al(OH)3)=_________。