问题 多项选择题 案例分析题

为保证生活饮用水卫生安全,保障人民健康,环境卫生工作者要重点掌握饮用水的卫生调查.监测和监督,包括对集中式给水的水源选择.水质的净化与消毒,水源水和饮用水的采样方法和饮用水的水质卫生监测与评价。

常用混凝剂优缺点比较,正确是()。

A.硫酸铝,腐蚀性小,使用方便,对水质无不良影响,水温低时形成絮状体较松散,效果不如铁盐

B.三氯化铁,适应的pH范围较广,絮状体大而紧密,对低温.低浊度水效果较铝盐好,但腐蚀性较强,易潮湿,水处理后铁量高

C.聚合氯化铝,腐蚀性小.成本低.适宜的pH范围较广,形成絮状体快,对低浊高浊水效果较好

D.聚合氯化铝,腐蚀性小.适宜的pH范围较广,但成本高,形成絮状体慢,对低浊高浊水效果均不好

E.硫酸铝,腐蚀性小,使用方便,对水质无不良影响,水温低时形成絮状体较紧密,效果较好,但成本高,适宜的pH范围较小

F.三氯化铁,腐蚀性小,使用方便,对水质无不良影响,水温低时形成絮状体较紧密,效果较好,但成本高,适宜的pH范围较小

答案

参考答案:A, B, C

阅读理解

     Summer is the ideal time of year for one of my favorite outdoor activities, hiking (徒步旅行). It is

much more than just a great Workout. You get to be outside of the confines of a gym and be together

with nature. You breathe in the fresh, clean air while the city life you endured all week just fades away.

You are suddenly transported somewhere else. You are suddenly in a place where you can appreciate

the untouched, simplistic beauty of nature. The trees are green, the wild flowers are growing and the

woods are filled with activity. Once you experience it, you're hooked.

     Whether hiking in the deserts of Arizona or the mountains of Alberta, you suddenly realize you are

not alone and there is something much bigger at work. There is a realization that life is precious and you

think deeply about your life.

     Another wonderful part of hiking is that you can participate at any level and it is, for the most part,

free. It is a great way to escape the rat race, even during the week. If you have any problems you need

to solve, hiking is really good for clearing your head and removing stress.

     If hiking sounds intimidating to you, it is essentially walking on a whole new level. Experts have

spoken about the benefits of walking for years. Walking doesn't stress your legs as much as running and

countless studies agree walking leads to weight loss and better health. It is good for your heart, reduces

illness and has even been shown to enhance your thinking. So why wouldn't you want to do it?

1. What disappears for someone who is hiking?

A. Green trees.

B. Beautiful nature.  

C. City life.    

D. Precious things.

2. Once you take up hiking in nature as something you do, you______.

A. feel much bigger than before

B. love it and want to do it often

C. wish you lived outside of the city

D. look for new hiking places, like Arizona

3. How do you feel after you've begun hiking?

A. Anxious.    

B. Thoughtful.    

C. Lonely.    

D. Free from stress.

4. How is running different than walking?

A. Running is harder on the legs.        

B. Running is better h/r weight loss.

C. Running is good for a person's heart.  

D. Running is a cause for improved thinking.

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