From New Delhi to Beijing，commuters（通勤者）spend a lot of time stuck in traffic．In the United States，Los Angeles（L．A．）and San Francisco tie for second place（并列第二）for having the worst traffic problems．Washington，D．C．is in first place with the worst traffic，according to the Texas A＆M Transportation Institute．
In L．A．．drivers spend sixty－one hours every year stuck in traffic．These drivers know all too well how bad the traffic can be．Professor Cyrus Shahabi also knows about traffic jams．He said，“It’s a prison of cars．There are too many cars，you can’t move around a lot．I live more than 65 kilometers from my office at the University of Southern California．in L．A．．I’m always late even with the help of a navigation（导航）system．I thought it would be appropriate to do something to solve it．”
Therefore，he and PhD student Ugur Demiryurek decided to develop an app for that．The ClearPath app claims to do what other navigation systems cannot．Professor Shahabi says his program uses historical data to predict traffic conditions even before the driver leaves the house．
ClearPath uses two and a half years worth of traffic data from 9，000 sensors（传感器）on the roads of L．A．．It also collects information on accidents．
Professor Shahabi says his system does more than just respond to current traffic conditions．With ClearPath，he says，a driver can enter what time he wants to leave on a specific time and date，and ClearPath will give the fastest route．It looks at the entire road network，including surface streets as well as highways，before the driver hits the road．
Ugur Demiryurek says they will launch the free ClearPath app for roads in L．A．in two months．In a year，he and Professor Shahabi hope to have ClearPath available nationwide and overseas once they can collect traffic data from other cities．
“I thought always that L．A．had the worst traffic，but now I know that Shanghai，Beijing，Seoul，Tokyo，believe it or not，Singapore，Hong Kong definitely are examples that can immediately use this．”
The ClearPath app can mainly be used to __________．

A．predict traffic conditions	B．kill the boring time
C．avoid the traffic accidents	D．collect the current news

What do we know from Professor Cyrus Shahabi’s words in Paragraph 2?

A．Living too far is his main reason for being late for work．

B．Many drivers broke the traffic rules on their way to work．

C．His invention was inspired by his experiences on his way to work．

D．The navigation system he used on his way to work is out of date．

What does Paragraph 5 mainly tell us about ClearPath?

A．Its working principal．	B．Its powerful function．
C．Its appearance．	D．Its safety．

What can we infer from the last paragraph?
A．L．A．has the worst traffic problems in the world．
B．Around the world ClearPath has been used widely．
C．Many cities can provide the data to do the study．
D．ClearPath will have a big market in the future．