请输入或粘贴题目内容
搜题
拍照、语音搜题，请扫码下载APP
题目内容
（请给出正确答案）
Laser beams can be used to bore metals and other hard materials.
A．trim
B．melt
C．drill
D．slice
答案
更多“Laser beams can be used to bore metals and other hard materials.A．trimB．meltC．drillD．slice”相关的问题
第1题
Which of the following is consistent with the passage？
A．Current rockets are vulnerable and unstable.
B．New propulsion system has been developed.
C．People consider laser beams as a possible solution to developing new propulsion system.
D．At present, nuclear energies can be used in propulsion systems.
第2题
A.light
B.heat
C.energy
D.radiation
第3题
The tool is the laser and it is being used by more and more surgeons all over the world. As we all know, light is hot, and any source of light will give warmth. But light is usually spread out over a wide area. The light in a laser beam, however, is concentrated. This means that a light with no more power than that produced by an ordinary electric light bulb becomes intensely strong as it is concentrated to a pinpoint-sized beam.
Experiments with these pinpoint beams showed researchers that different energy sources produce beams that have a particular effect on certain living cells. It is now possible for eye surgeons to operate on the back of human eye without harming the front of the eye, simply by passing a laser beam right through the eye-ball. Operations which once left patients exhausted and in need of long period of recovery time now leave them feeling relaxed and comfortable.
The rapid development of laser techniques in the past ten years has made it clear that the future is likely to be very exciting. Perhaps some cancers will be treated with laser in a way that makes surgery not only safer but also more effective.
Which of the following would be appropriate to describe the instruments of surgical operations up until 1960s？
A．Traditional.
B．Complicated.
C．Remarkable.
D．Revolutionary.
第4题
请根据短文内容，回答题。
Compact Disks
If someone says to you your music CDs don&39;t really hold any music on them, and they only have numbers recorded on them, you may not believe it. In fact, he is right in that sound is actually recorded onto the CDs as special numbers--a digital code. The code is pressed onto the CD as bumps (隆起 )on a long spiral track almost five kilometers long. These bumps are an average of 0.5 microns (微米) wide.＜br＞
A small laser beam shines onto the bumps as the CD turns. The light is reflected back to a receiver that records how the laser light bounces back. This lets the CD player turn the reflected light back into the original code. This means you can hear the original code as music.＜br＞
Digital codes are used with many technologies. E-mail needs these kinds of code numbers.＜br＞
Space probes (探测仪) communicate with their ground station on earth using digital codes. Bar codes are read as digital codes in computer systems. Digital communications with cell phones need digital codes. Weather radios also tune in to specific signals using these codes.＜br＞
There are many types of compact disks. One format is called CD-RWs. They can be recorded on and re-recorded on (rewritten on) as you would do with a floppy disk (软盘). Another format is the CD-ROM. The technology for recording on these disks is different from other CDs. These CDs have a dye layer that the CD writer can darken or leave clear. The clear and dark spots are the digital code. CD-ROM stands for Compact Disc--Read Only Memory. This disk is like a "super"floppy disk that can hold lots of information. One CD-ROM can hold the same amount of data as 500 floppy disks. Information is permanently recorded onto it. Computer games and other programs are＜br＞
considered to be CD-ROMs.＜br＞
CDs were first sold to the public in 1982. These CDs still play well and sound fine. Current CDs are expected to last between 70 to 200 years. Of course, you can make sure your CDs last a long time by taking care of them.＜br＞
Science keeps on developing. It may not be many more years before a completely new technology is invented and introduced to the public for music recording. In the meantime, there is no doubt you will continue to enjoy listening to your favorite music on CDs and playing your favorite computer games on CD-ROMs.
Music is recorded onto CDs as __________. 查看材料
A.laser beams
B.digital codes
C.musical notes
D.special sounds
第5题
A laser beam can be turned into a ______ weapon.
A) dead B) dying C) deadly D) deathly
第6题
After the use of the laser beam, surgeons can perform. operation which ______.
A．leave their patients with negative effects
B．can treat duly human eye diseases
C．do little damage to their patients
D．make their patients need a long time to recover
第7题
A.Drum
B.Inkjet
C.Dot-matrix
D.Laser
第8题
A laser can be best described by______.
A．a device for stimulating atoms and molecules to emit light
B．an atom in a high energy state
C．a technique for destroying atom or molecules
D．an instrument for measuring light waves
第9题
What is the talk mainly about？
A．Computer lab services.
B．College library facilities.
C．The use of micro-computers.
D．Printouts from the laser printer.
第10题
After the use of the laser beam, surgeons can perform. operation which
A．leave their patients with negative effects
B．can treat only human eye diseases
C．do little damage to their patients
D．make their patients need a long time to recover
