Last night, when I was nearly asleep, I saw a figure ________ in the room.

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Many companies use guards and expensive alarm systems to protect their property (財(cái)產(chǎn)). Soon a new kind of protection will be used—robots. Engineers have been working on the first mobile robots for businesses. The robots will guard factories, warehouses (倉(cāng)庫(kù)) and museums at night.
The mobile robots will move around slowly on wheels. They will be able to detect (察覺(jué),發(fā)現(xiàn)) people through walls and pick up sounds, such as breaking glass. They can be fixed with loud sirens to frighten thieves, or radios to signal police or guards.
To protect a building, a robot will have to move around without knocking into the walls. Information about the building will have to be stored in the robot’s small, built-in computer. A floor map could be programmed into the computer’s memory, for example.
A mobile robot will not be able to do everything. Unlike human guards, it will not be able to climb stairs, open doors, or move along rough ground. It won’t be able to tell the difference between friends and enemies. Because of that, people will have to be prevented from entering the area it moves.
One kind of mobile robot will be able to “sense” whether a chair or a box has been moved and go around it. This robot will also judge size well enough so that it won’t send an alarm if a cat crosses the room. And if someone tries to steal this robot, it will sound a loud, painful siren. The three-foot-tall robot is hard to be stolen anyway. It weighs about 200 pounds.
U.S. companies pay almost $10 billion a year to protect their property with alarm systems and human guards. Mobile robots may be cheaper.  (296)
【小題1】 Why is the new kind of robots called mobile robots? Because they can _____.

You have often __1__ people talk about work. Perhaps you have __2__ your friends about how hard you worked to get something done. However, you may have done no work __3_ you think you worked hard.

A boy is pushing a big box very hard, but the box is __4__ heavy for him to move and he may __5__ to push against the box. __6__ the language of science, he has not done __7__ work. Can you think you are working when you are studying or talking?

In science, work is only done when a force(力) moves something that has weight through a distance（距離）.

Work =" force" × distance moved.

__8_ you want to find out whether work is done, _9_ yourself, “Is a push or a pull moving something through a distance?” If your answer is __10_, then work is being done.