Question

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     Plants can't communicate by moving or making sounds, as most animals do. Instead, plants produce
volatile compounds, chemicals that easily change from a liquid to a gas. A flower's sweet smell, for example,
comes from volatile compounds that the plant produces to attract insects such as bugs and bees.
     Plants can also detect volatile compounds produced by other plants. A tree under attack by hungry insects,
for instance, may give off volatile compounds that let other trees know about the attack. In response, the other
trees may send off chemicals to keep the bugs away-or even chemicals that attract the bugs' natural enemies.
     Now scientists have created a quick way to understand what plants are saying: a chemical sensor (传感器)
called an electronic nose. The "e-nose" can tell compounds that crop plants make when they're attacked.
Scientists say the e-nose could help quickly detest whether plants are being eaten by insects. But today the only
way to detect such insects is to visually inspect individual plants. This is a challenging task for managers of
greenhouses, enclosed gardens that can house thousands of plants.
     The research team worked with an e-nose that recognizes volatile compounds. Inside the device, 13 sensors
chemically react with volatile compounds. Based on these interactions, the e-nose gives off electronic signals
that the scientists analyze using computer software.
     To test the nose, the team presented it with healthy leaves from cucumber, pepper and tomato plants, all
common greenhouse crops. Then the scientists collected samples of air around damaged leaves from each type
of crop. These plants had been damaged by insects, or by scientists who made holes in the leaves with a hole
punch (打孔器).
     The e-nose, it turns out, could identify healthy cucumber, pepper and tomato plants based on the volatile
compounds they produce. It could also identify tomato leaves that had been damaged. But even more impressive,
the device could tell which type of damage - by insects or with a hole punch-had been done to the tomato leaves.
     With some fine tuning, a device like the e-nose could one day be used in greenhouses to quickly spot harmful
bugs, the researchers say. A device like this could also be used to identify fruits that are perfectly ripe and ready
to pick and eat, says Natalia Dudareve, a biochemist at Purdue University in West Lafayette, Ind. who studies
smells of flowers and plants. Hopefully, scientists believe, the device could bring large benefits to greenhouse
managers in the near future.

1. We learn from the text that plants communicate with each other by _____.

A. making some sounds
B. waving their leaves
C. producing some chemicals
D. sending out electronic signals

2. What did the scientists do to find out if the e-nose worked?

A. They presented it with all common crops.
B. They fixed 13 sensors inside the device.
C. They collected different damaged leaves.
D. They made tests on damaged and healthy leaves.

3. According to the writer, the most amazing thing about the e -nose is that it can _____.

A. pick out ripe fruits
B. spot the insects quickly
C. distinguish different damages to the leaves
D. recognize unhealthy tomato leaves

4. We can infer from the last paragraph that the e-nose _____.

A. is unable to tell the smell of flowers
B. is not yet used in greenhouses
C. is designed by scientists at Purdue
D. is helpful in killing harmful insects

Answer 1

1-4: C D C B