问题 选择题

下列关于配制20%氢氧化钠溶液的说法错误的是(  )

A.把10g氢氧化钠和40mL水混合、搅拌、装瓶、贴标签

B.用到的仪器有天平、量筒、药匙、胶头滴管、烧杯和玻璃棒

C.称量氢氧化钠时,天平的左右盘里都要放上相等质量的纸片

D.量取水时仰视量筒刻度可导致所配制的溶液质量分数偏小

答案

A.把10g氢氧化钠和40mL水混合,溶质的质量分数=

10g
10g+40g
×100%=20%;搅拌、装瓶、贴标签,正确;

B.配置溶液用到的仪器有天平、量筒、药匙、胶头滴管、烧杯和玻璃棒,正确;

C.称量氢氧化钠时,因为氢氧化钠有腐蚀性,应放在玻璃器皿里;错误;

D.量取水时仰视量筒刻度可导致量的水比读数多,故可导致所配制的溶液质量分数偏小,正确.

答案:C

问答题

American and Japanese researchers are developing a smart car that will help drivers avoid accidents by predicting when they are about to make a dangerous move.

The smart car of the future will be able to tell if drivers are going to turn, change lanes, speed up, slow down or pass another car.

If the driver’s intended action could lead to an accident,the car will activate a warning system or override the move.

(46) " BY shifting the emphasis of car safety away from design of the vehicle itself and looking more toward the driver’s behavior, the developers believe that they can start to build cars that adapt to suit people’s needs , " New Scientist magazine said.

Alex Pentland of the Massachusetts Institute of Technology collaborated on the project with Andrew Liu who works for the Japanese carmaker Nissan.

(47)Tests of their smart car using a driving simulator have shown that it is 95 percent accurate in predicting a driver’s 12 seconds in advance.

(48)The system is based on driving behavior which the researchers say can be divided into chains of sub-actions which include preparatory moves.

It monitors the driver’s behavior patterns to predict the next move.

" To make its predictions, Nissan’s smart car uses a computer and sensors on the steering wheel, accelerator and brake to monitor a person’s driving patterns. (49)A brief training session, in which the driver is asked to perform certain maneuvers, allows the system to calculate the probability of particular actions occurring in two-second time segments, " the magazine said.

Liu has also done work on tracking eye movement to predict driving behavior. (50)He said the smart car could be adapted to monitor eye movement which could give even earlier predictions of when a driver is about to make a wrong move.

(49)A brief training session, in which the driver is asked to perform certain maneuvers, allows the system to calculate the probability of particular actions occurring in two-second time segments, " the magazine said.

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