1．A.small　 　　　　　 　B．basic　　　　　　　　　　 C．necessary　　　　　　　　 　 D．large

5．The new sensor system could let engineers know ________.

A．how to solve traffic problems

B．which bridge is designed best

C．when the bridge repair is necessary

D．what suspension bridges mean to a city

4．Many suspension bridges in America are in need of super repairs because ________.

A．they are too old and the style is out of date

B．many steel cables are too rusty

C．they can’t meet the development of modern traffic system

D．they have withstood lots of years of wear and tear from heavy traffic and severe weather

3．Engineers at Columbia University in New York City use new technology to ________.

A．design a new suspension bridge

B．see the lifespan of big suspension bridges

C．prevent suspension bridges from corrosion

D．solve the traffic delays caused by bridge maintenance

2．In the testing system，the engineers are trying to ________.

A．create real­world conditions that are as aggressive as the ones out there

B．replace old suspenders with new ones

C．break the suspender apart to see the inside of it

D．put as much weight as possible that the bridge can bear

1．Which of the following could be the image of the bridge described in the passage?

20．A.recall　 　　　 　　B．refocus　　　　　　 C．rebuild 　　　　　 D．reunite

2

Some of the largest，longest，and most beautiful bridges in the world are suspension bridges.Although suspension bridges look impressively complicated，their design is relatively simple.Giant cables are strung between two towers that are anchored (固定) to land on either side of a waterway or land gorge.The road hangs from the giant cables by suspension cables，or suspenders.Suspenders are made by weaving together thousands of thick steel strands.

Even though these superstructures are built to last，many of American suspension bridges are getting old.The Golden Gate Bridge is slightly more than 70 years old.The Brooklyn Bridge in New York City celebrated its 125th birthday in 2008.Many of these superstructures are in need of super repairs.

Engineers at Columbia University in New York City have set out to create a way to detect the lifespan of a suspension cable electronically.They are testing a system in which tiny sensors are embedded (嵌入) inside cable strands to monitor a suspender’s condition around the clock.

Engineer Raimondo Betti and his team at Columbia built a lab last December.They will use heat lamps to simulate the temperature changes a suspender would have to endure through changing seasons.They will shower the test cable with water and road salt to see how it withstands rain and snow conditions.In addition to blasting the suspender with severe weather conditions，the engineers are also subjecting the cable to the same kind of weight of a suspender on a high­traffic bridge would have to bear.The team will record data from the sensors over the next six months.After that，they will open the cable and see the extent to which the data they’ve recorded matches the actual damage to the cable.

Betti says more accurate information on cable corrosion will be of great use to cities and states.Bridge owners will be able to make more informed decisions on maintenance and repair plans for bridges.

19．A.meant　 　　　 　　B．demanded　　　　　　　　 C．forced　 　　　　　 D．aimed

18．A.goals　 　　　 　　B．interests　　　　　　　　　　 C．personality　 　 D．consideration

17．A.in　 　　　　　B．to　 　　　　　　　　　　　　 C．by　 　　　　　　　 D．at