Ｆｌｙｉｎｇ?。簦瑁濉。龋穑澹颉。樱耄椋澹?/h1>
2009-05-26 07:31:56
中學(xué)科技 2009年4期
A little airplane has given new meaning to the term "going hyper".
The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound. That's about 5000 miles per hour. At this speed, you'd get around the world - flying along the equator - in less than 5 hours.
The Hyper-X is an unmanned, experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet. It may sound like something from a comic book, but engineers have been experimenting with scramjets since the 1960s.
For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet engine goes as fast as a rocket, but it doesn't have to carry its own oxygen supply.
A scramjet's special design allows it to extract oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound.
A booster rocket carried the Hyper-X to an altitude of about 100000 feet for its test flight. The aircraft's record-beating flight lasted just 11 seconds.
In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Hypersonic airliners could carry passengers anywhere in the world in just a few hours.
Out of the three experimental Hyper-X aircraft built for NASA, only one is now left. The agency has plans for another, 11-second hypersonic flight, this time at 10 times the speed of sound.
1. The passage introduces a new kind of aircraft which can fly _____.
A. without burning oxygen
B. withoutcarryingitsown oxygen
C. beyond the earth'satmos-phere
D. as fast as sound
2. Ascramjetenginediffers from a rocket engine in that _____.
A. it can fly much faster than the latter
B. it is much larger in size than the latter
C. it gets its fuel in the process of flying
D. itallowstheplanetocarry passengers as well as cargos
3.According to the passage, _____.
A. the test flight of the Hyper-X was a failure
B. the Hyper-Xistoosmallto be of any practical use
C. the Hyper-X canfly no long-er than eleven seconds
D. thespeedoftheHyper-X aircraft can be further increased
Smash the Old Computer
Ifyou are planning on getting ridofan old computer, make sure you (A) r_____the hard drive first and smash it up with a hammer.
Computer scientists say the only way to make sure fraudsters could not steal (B) p_____details from an old computers hard drive was to utterly destroy it, as simply deleting files or wiping the drive was not (C) s_____. Once a scientist bought eight second-hand drives from internet auction site eBay and recovered 22000 "deleted files", including some (1) i_____ that could be confidential. He did it just as an (2) e_____, but the results of his experiment (D) i_____ how easy it is for criminals to recover the "deleted files" if they really want to. Even if they have got such skills, they still could use specialist software to (3) r_____the information, which could then be used to (4) c_____identity theft.
PCs contain more (5) v_____personal information than ever as people increasingly shop online, use social networking sites and take digital photos. Even if you delete your files, you'd be surprised how easy it is to recover your personaldata.It sounds extreme, but the only way to be 100 percent sate is to smash your hard drive into smithereens with a (E) h _____ .
(A, B, C, D, E FOR CROSS, 1, 2, 3, 4, 5 FOR DOWN. The first letters of the absents were given)
Find the Better Bargain
Which is the better bargain: A shirt that is marked down 10 percent from its original price and then reduced an additional 40 percent, or the same shirt reduced 50 percent from its original price?
A. not enough information
B. 10 percent then 40 percent
C. 50 percent
D. Neither-they are the same
上期Crossword答案
1. participant 2. flow
3. pointing4. visual
5. gained A. control
B. randomlyC. adaptable
上期Illation答案
Correct answer: D
The condition that one of the guilty ones was telling the truth is key. The only persons who could possibly be guilty and tell the truth are Jack or Jared. If Jared is the guilty one telling the truth, then the only possible pair is Jack and Jared. However, this means that Jack is also telling the truth, thus it is not an option. it tells that Jack has to be the guilty one telling the truth, and that neither John nor Justin could be guilty, or else Jack's statement would be false. We've already ruled out Jack and Jared as partners, so the only two possible pairs left are Jack and Jim, Jack and Joe. In both of these cases, the conditions for liars and truth-tellers are met, so there is no way to tell who was Jack's accomplice.
A little airplane has given new meaning to the term "going hyper".
The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound. That's about 5000 miles per hour. At this speed, you'd get around the world - flying along the equator - in less than 5 hours.
The Hyper-X is an unmanned, experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet. It may sound like something from a comic book, but engineers have been experimenting with scramjets since the 1960s.
For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet engine goes as fast as a rocket, but it doesn't have to carry its own oxygen supply.
A scramjet's special design allows it to extract oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound.
A booster rocket carried the Hyper-X to an altitude of about 100000 feet for its test flight. The aircraft's record-beating flight lasted just 11 seconds.
In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Hypersonic airliners could carry passengers anywhere in the world in just a few hours.
Out of the three experimental Hyper-X aircraft built for NASA, only one is now left. The agency has plans for another, 11-second hypersonic flight, this time at 10 times the speed of sound.
1. The passage introduces a new kind of aircraft which can fly _____.
A. without burning oxygen
B. withoutcarryingitsown oxygen
C. beyond the earth'satmos-phere
D. as fast as sound
2. Ascramjetenginediffers from a rocket engine in that _____.
A. it can fly much faster than the latter
B. it is much larger in size than the latter
C. it gets its fuel in the process of flying
D. itallowstheplanetocarry passengers as well as cargos
3.According to the passage, _____.
A. the test flight of the Hyper-X was a failure
B. the Hyper-Xistoosmallto be of any practical use
C. the Hyper-X canfly no long-er than eleven seconds
D. thespeedoftheHyper-X aircraft can be further increased
Smash the Old Computer
Ifyou are planning on getting ridofan old computer, make sure you (A) r_____the hard drive first and smash it up with a hammer.
Computer scientists say the only way to make sure fraudsters could not steal (B) p_____details from an old computers hard drive was to utterly destroy it, as simply deleting files or wiping the drive was not (C) s_____. Once a scientist bought eight second-hand drives from internet auction site eBay and recovered 22000 "deleted files", including some (1) i_____ that could be confidential. He did it just as an (2) e_____, but the results of his experiment (D) i_____ how easy it is for criminals to recover the "deleted files" if they really want to. Even if they have got such skills, they still could use specialist software to (3) r_____the information, which could then be used to (4) c_____identity theft.
PCs contain more (5) v_____personal information than ever as people increasingly shop online, use social networking sites and take digital photos. Even if you delete your files, you'd be surprised how easy it is to recover your personaldata.It sounds extreme, but the only way to be 100 percent sate is to smash your hard drive into smithereens with a (E) h _____ .
(A, B, C, D, E FOR CROSS, 1, 2, 3, 4, 5 FOR DOWN. The first letters of the absents were given)
Find the Better Bargain
Which is the better bargain: A shirt that is marked down 10 percent from its original price and then reduced an additional 40 percent, or the same shirt reduced 50 percent from its original price?
A. not enough information
B. 10 percent then 40 percent
C. 50 percent
D. Neither-they are the same
上期Crossword答案
1. participant 2. flow
3. pointing4. visual
5. gained A. control
B. randomlyC. adaptable
上期Illation答案
Correct answer: D
The condition that one of the guilty ones was telling the truth is key. The only persons who could possibly be guilty and tell the truth are Jack or Jared. If Jared is the guilty one telling the truth, then the only possible pair is Jack and Jared. However, this means that Jack is also telling the truth, thus it is not an option. it tells that Jack has to be the guilty one telling the truth, and that neither John nor Justin could be guilty, or else Jack's statement would be false. We've already ruled out Jack and Jared as partners, so the only two possible pairs left are Jack and Jim, Jack and Joe. In both of these cases, the conditions for liars and truth-tellers are met, so there is no way to tell who was Jack's accomplice.
