“经济上落后的国家在哲学上仍然能演奏第一提琴”。恩格斯这段话说明了 A．文化是对

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     Tongue clicking is an important part of language for some southern African groups. And it could help

disabled people control their wheelchairs. The key is a device that is put in the ears and listens for tongue

clicks and then translates the sounds into commands for a wheelchair.

     Mouth interfaces (接口)that interact with wheelchairs are already common for seriously disabled

people. One device that fits within the roof of the mouth houses buttons that can be pressed with the

tongue.

     "But everything that involves tongue movement requires putting something in the mouth," says Ravi,

from the University of Bristol, UK. Besides issues of hygiene (卫生),these devices make it difficult for

the user to eat or speak, if they are able to ,while using it. Monitoring tongue movements through the ear

avoids these problems.

     The new device, a simple microphone that looks like an earphone for listening to music, picks up

certain sounds made by four sorts of tongue clicks. The microphone sends the information to a signal

processor which sorts out the clicks and passes the information to the wheelchair, where each click type

moves the chair in a distinct direction.

     Ravi's group has used the interface to control a virtual wheelchair. They have also used it to control

the reaching and grasping movements of a robotic arm. The four tongue clicks can be mastered in a

couple of hours, say the researchers. "This is a promising technique," says Jose del R. Millan, who has

been working on brain interfaces for controlling wheelchairs at the Swiss Federal Institute of Technology

in Lausanne. If it can be combined with real wheelchairs and shown to work reliably it could be very

valuable for patients, he says.

      The researchers plan to start using real wheelchairs, but in the meantime they are looking at whether

the number of commands can be increased by using a microphone in each ear, to get clearer signals to

the wheelchairs. "Even if four clicks prove to be the limit, it only takes 0.2 second to detect each sound,

so it's possible to spread high-level commands through combinations of clicking sounds," the researchers

say.

1. What plays the most important role in controlling the wheelchair by tongue clicking?

A. The tongue.

B. The device.

C. The wheelchair.

D. the brain.

2. What problem will be caused if mouth interfaces are used to monitor the wheelchair?

A. It is very difficult to operate the device.

B. The device is dirty and leads to disease.

C. The device makes it difficult for people to eat or speak.

D. People are disturbed by the device when listening.

3. What do we know about the new device according to the passage?

A. It is actually an earphone used to listen to music.

B. It hasn't been put into practice to control wheelchairs.

C. It can pick up all sounds made by tongue clicks.

D. It can give orders where the wheelchair should go .

4. What problem are Ravi and his groups trying to solve now?

A. That the device can't detect more commands.

B. That it needs a long time to detect each sound.

C. That it can only combine some easy tongue clicks.

D. That it takes a long time for the disabled to learn tongue clicks.

肥料的三要素是指（）。

A.氮、磷、钾

B.硼、磷、钾

C.氮、硼、磷

D.氮、硼、硫

垫片属于（）的填料。

A、静密封

B、动密封

C、机械密封

D、非接触密封