更多"Invisibility Ring Scientists can’t"的相关试题:
[单项选择]
Invisibility Ring
Scientists can’t yet make an invisibility cloak like the one that Harry Potter uses. But, for the first time, they’ve constructed a simple cloaking device that makes itself and something placed inside it invisible to microwaves.
When a person "sees" an object, his or her eye senses many different waves of visible light as they bounce off the object. The eye and brain then work together to organize the sesensations and reconstruct the object’s original shape. So, to make an object invisible, scientists have to keep waves from bouncing off it. And they have to make sure the object casts no shadow. Otherwise, the absence of reflected light on one side would give the object away.
Invisibility isn’t possible yet with waves of light that the human eye can see. But it is now possible with microwaves. Like visible light, microwaves are a form of radiant energy. They are part of the electromagnetic spectrum, which also
A. Their wave lengths are shorter than those of visible light.
B. Their wave lengths are longer than those of visible light.
C. They are different from visible light as they are a kind of radiant energy.
D. They are visible to the human ey
[填空题]How can people make use of sea water
They make use of it by （） the salt.
[单项选择]
Why can’t the man ring the woman
A. He hasn’t got a telephone.
B. He is unfortunate.
C. His telephone doesn’t work,
D. He doesn’t have time.
[单项选择]While it can’t yet be said that every mouthful of food has been changed through genetic engineering, it is likely that almost every American has had a mouthful of engineered food.
Take the soybean, for example. About 55 percent of last year’s crop was genetically engineered in some fashion, reports the American Soybean Association. And though few Americans sit down to a plate of soybeans for dinner, these soybeans arrive through the back door as an additive to scores of foods like cooking oils, salad dressings, coffee creamers, beer, cereals and candy.
America is on the verge of a second green revolution. The first tripled world food output over the course of a mere three decades during the late 20th century. Scientists boosted crop yields by crossbreeding (杂交) related plants that add desirable traits. Then farmers added fertilizer, pesticide, and irrigation in order to make the high-yield crops thrive.
Now that those gains are leveling off, scientists are looking to bio
A. To crossbreed the related plants.
B. To add the desirable traits to the plants.
C. To realize the green revolution in three decades.
D. To make the high-yield crops thrive.
[单项选择]We can make an exception（）
A. in any case of John
B. in case of John
C. in case of John’s
D. in the case of John
[填空题]The greatest difference people can make relatively easily is with ______.
[填空题]The invisibility cloak can make something invisible by wrapping ______.
[填空题]People can make clothes with it.
[填空题]You can make others understand something.
