问题 填空题

某山区饮用的水常是河水,由于河水中常含有泥沙等固体小颗粒和细菌等杂质。用次氯酸(HClO)杀死细菌,将漂白粉(主要成分是Ca(ClO)2)溶于水可生成可溶性氯化钙和次氯酸。下列是某户居民在饮用水之前对河水的处理步骤:

河水→A(明矾)→B(沉淀)→C(过滤)→D(活性炭)→E(漂白粉)→净水

(l)可以除去固体小颗粒的步骤是    (填编号);A步中加明矾的作用是   

C步中玻璃棒的作用是       ,经过上述净水步骤   (填“能”或“不能”)使硬水软化。

(2)能够消毒杀菌的步骤为       (填编号);加漂白粉杀菌发生的是     (填“物理”或“化学”)变化。

(3)该户居民得到的净水是纯净物,还是混合物         ,其原因是

(4)小明对一杯浑浊的水进行过滤后发现滤液仍然是浑浊的,造成过滤失败的可能原因有哪些?(任写两点)                                           

答案

(1)C;吸附杂质,使其沉降;引流,防止液体外洒;不能(每空1分)

(2)E;化学(每空1分)

(3)混合物;水中还有许多可溶性杂质(每空1分)

(4)液面高于滤纸边缘;滤纸被捅破了;或承接滤液的烧杯不干净(每空2分)

题目分析:过滤可以除去水中的固体不溶物,不能除去溶于水的物质,不能使硬水软化,属于物理过程,过滤操作中要注意“一帖二低三靠”;用消毒剂对水消毒是化学过程。

题中除去固体小颗粒的步骤是过滤,加明矾的作用是吸附杂质,使其沉降,玻璃棒的作用是引流,防止液体外洒,要使水软化,得用煮沸或者蒸馏的方法;过滤消毒后的水还是混合物,只有蒸馏得到的蒸馏水才是纯净物。过滤实验过程中,要保证仪器干净,操作方法正确,假如出现液面高于滤纸边缘;滤纸被捅破等情况就容易导致实验失败。

点评:水的净化是常考的题目,经常涉及过滤操作、纯净物和混合物的区分,还有自来水的生产等方面内容。

完形填空
We’ve all done it at one point or another. You’re driving along to work or school when that familiar sound reaches your eardrums(耳膜). You look down, reach into your pocket and begin to read, your steering wheel(方向盘) in one hand, your phone in the other. As you respond to that text message from your friend, you look intermittently(间歇地) at the road, and then back down at your phone. You’ve done it plenty of times before. What can go wrong?
What do you think is the number one killer of teenagers in the U.S.? Drugs? Alcohol? Violence? The answer is distracted driving. According to the National Safety Council, over 24 percent of all motor vehicle crashes involve cell phone use. Either a quick 30-second phone call or a simple text reading may be the cause of a traffic accident. In addition, drivers who talk on a cell phone, whether hands-free or not, are four times more likely to crash.
The risk of teenagers getting into an accident rises sharply. According to keepthedrive.com, more than 3,000 teenagers die in car accidents each year with about another 450,000 teenagers being injured. Additionally, according to a University of Utah study, reading or sending even one text message is equal to having a 0.08 alcohol level. In most states, that is considered as drunk-driving.
So, how do you prevent yourself from the danger of distracted driving? The answer is simpler than you might think. Put your phone away. Mute(消音) your phone or just turn it off while driving. If you still can’t help reaching for your phone, throw it on the backseat. This way, you won’t be able to get to it until you arrive at your destination.
You may get away with talking on the phone now, but there may be a day when you don’t. Dropping your phone may be an inconvenience, but it’s better than being a victim of your distracted driving.
Title: The danger of reading and texting on the phone while driving
小题1:_______
Drivers are used to reading and小题2:___ to text messages while driving.
小题3:___ of
distracted driving
 About a quarter of all motor vehicle crashes are 小题4:___ to cell phone use.
Drivers talking on a cell phone have a much stronger 小题5: of crashing.
The rising risk of teenagers getting into accidents
 A number of teenagers get 小题6:_____ in or even die from car accidents every year.
Reading or sending one text message while driving 小题7:____ having a 0.08 alcohol level.
小题8:___ of preventing distracted driving
 Mute your phone or turn it off to keep you concentrated on driving.
Put your phone out of your 小题9:___ while driving.
Conclusion
It may be not 小题10:___ for you to drop your phone but you can protect your self from hurt or death.
单项选择题