英语论文网

that seems to be killing many species of amphibians in different parts of the world.
All these reasons for the disappearance of amphibians are also good reasons for more general concern. The destruction of land， the pollution of the air and the water， the changes in our atmosphere， the spread of diseases - these factors affect human beings， too. Amphibians are especially sensitive to environmental change. Perhaps they are like the canary （金丝雀） bird that coal miners once used to take down into the mines to detect poisonous gases. When the canary became ill or died， the miners knew that dangerous gases were near and their own lives were in danger.
36 Losing amphibians means losing
A.knowledge about fatal human diseases.
B.knowledge about air and water pollution.
C.a chance to discover new medicines.
D.an opportunity to detect poisonous gases.
37 Amphibians lay their eggs
A.in any stream they can find，
B.in places without UV light，
C.only on sand.
D.only in the right conditions
38 The arroyo toad is disappearing because
A.it has been threatened by frogs.
B.it is losing its habitat.
C.a disease has been killing its eggs.
D.it can’t bear the cold of winter.
39 Coal miners once used the canary bird to detect
A.poisonous gases.
B.air pollution.
C.water leakage.
D.radiation.
40 Scientists think that the decline of amphibians could
A.cause environmental change.
B.cause a decline in other kinds of animals.
C.be a warning signal for human beings.
D.be a good sign for human beings.
第三篇
Controlling Robots with the Mind
Belle， our tiny monkey， was seated in her special chair inside a chamber at our Duke University lab. Her right hand grasped a joystick （操纵杆） as she watched a horizontal series of lights on a display panel. She knew that if a light suddenly shone and she moved the joystick left or right to correspond to its position， she would be sent a drop of fruit juice into her mouth.
Belle wore a cap glued to her head. Under it were four plastic connectors， which fed arrays of microwires-each wire finer than the finest sewing thread- into different regions of Belle’s motor cortex （脑皮层）， tile brain tissue that plans movements and sends instructions. Each of the 100 microwires lay beside a single motor neuron （神经元）。 When a neuron produced an electrical discharge， the adjacent microwire would capture the current and send it up through a small wiring bundle that ran from Belle’s cap to a box of electronics on a table next to the booth. The box， in turn， was linked to two computers， one next door and the other half a country away.
After months of hard work， we were about to test the idea that we could reliably translate the raw electrical activity in a living being’s brain-Belle’s mere thoughts-into signals that could direct the actions of a robot. We had assembled a multijointed robot arm in this room， away from Belle’s view， which she would control for the first time. As soon as Belle’s brain sensed a lit spot on the panel， electronics in the box running two real-time mathematical models would rapidly analyze the tiny action potentials produced by her brain cells. Our lab computer would convert the electrical patterns into instructions that would direct the robot arm. Six hundred miles north， in Cambridge， Mass， a different computer would produce the same actions in another robot arm built by Mandayam A　Srinivasan. If we had do