题目内容
（请给出正确答案）
A、the applied potential causes the n-type material to be more positive than the p-type material
B、the applied potential causes the n-type material to be more negative than the p-type material
C、both materials are at the same potential
D、None of these
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（由简答题聘请的专业题库老师提供的解答）
更多“A p-n junction is forward biased when ____.”相关的问题
A、when will we start our journey
B、when we will start our journey
C、If we will start our journey
D、will we start our journey
A、took
B、brought
C、showed
D、came
| 阅读理解 |
| When I was a girl of 16, I met a common boy who would make jokes at you and then you would run after him and his guys and beat them up(打闹). After that first meeting, we kept on meeting and beating each other up at the fence. We would meet at the fence all the time and we were always together. I would tell him all my secrets. I found him easy to talk to and I could talk to him about everything. In school we had separate friends. One day I told him that a guy I liked hurt me and broke my heart. He just comforted me and said everything would be okay. He gave me words of encouragement and helped me get over him. I was happy and thought of him as a real friend. But I knew that there was something else about him that I liked. I thought of it that night and figured it was just a kind of friend that I was feeling. All through high school and even through graduation we're always together and of course I thought of it as being friends. But I knew deep inside that I really felt it differently. On graduation night even though we had different dates to the dance I wanted to be with him. That night after everybody went home, I went to his house and wanted to tell him that I wanted to see him. Well, that night was my big chance and all I did was just sit there with him watching the stars and talking about what I was going to do and what he was going to do. I looked into his eyes and listened to him talk about what his dream was, and how he wanted to get married and settle down. He said how he wanted to be rich and successful. All I could do was to tell him my dream and sit next to him. I went home hurting because I didn't tell him how I was feeling. 1. The first sentence in Paragraph 1 describes a kind of____relationship. A. normal B. special C. dangerous D. harmful 2. From the Paragraph 2, we can learn the following are boy's advantages but____. A. communicating with others B. understanding others C. giving girls better impression D. comforting others 3. The author tells the story in a way of____. A. anger B. regret C. excitement D. anxiety 4. The author felt hurt on graduation night because____. A. they would have no opportunity to meet again B. she failed to express her true feeling C. the boy did understand her D. she got poor grades in her study |
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.
The first innovation in the design of combat binoculars(双筒望远镜)in over 200 years is on the horizon. The device, called "talking binoculars", is derived from the strategic satellite-to-satellite communications program. The idea is to use one pair of binoculars to project a laser beam to carry a scout's' observations to a second pair as the receiver.
Military scouts today cannot use radios during radio silent scouting missions inside enemy territory because the enemy can detect and locate their transmissions. With the new "talking" binoculars, when a forward military scout sees the enemy through transmitting laser binoculars and depresses the target locate and store button, global positioning system technology will measure the enemy's target position. Then, the binoculars store the information and use its invisible laser beam to transmit the enemy's position to a receiving set of binoculars. The receiving scout can then immediately transmit target data back to the lines. The military scout will no longer need maps, have to depend on written notes, or leave a position to report back to the commander.
The innovative binoculars also solve the aged-data problem by relaying the military scout's observations in near-real time to the commander in the tactical(战术的) operations center. The scout does not need to personally return to lines to make a report which is aged by the time the commander receives it.
"Enemy detection of the binoculars is near impossible because the weak laser beam is projected from point to point," Strickland said. "An enemy searching for a weak' laser source requires sensitive optical detectors and must be near the receiver to detect the weak laser. It will be much easier for the scout to see the enemy than for the enemy to detect the laser beam. By comparison, radio broadcast is transmitted in all directions, allowing easy detection by a prepared enemy from all angles." he said.
Digital laser communications is a valuable technology. Its advantage stems from providing high data rate communications capability when the mission prevents scouts from using their radios. A weak laser beam can carry digitized voice messages, targeting data and high-quality video images at extremely high data rates.
Military planners are already envisioning a day when all communications on a battlefield, between tanks or between tanks and helicopters, to name only two examples, are transmitted by laser. Theoretically, a laser-based communications system could handle 200,000 voice channels. Currently, even the most powerful high-capacity lasers, capable of transmitting 100 TV channels, weigh only 29 pounds, so they are easily deployed on vehicles or aircraft. In the future, lasers may also transmit information directly from orbiting satellites.
Without the talking binoculars, a scout during radio silent scouting missions ______.
A．can be easily detected and located by the enemy
B．is not able to determine the enemy's target position
C．has to make a record of what he has observed
D．risks getting caught when returning to report back
A、-2000
B、-1/50
C、50
D、-48.78
A、is large
B、is small
C、is forward-biased
D、is reverse-biased
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