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A new kind of radar has been developed for spaceship travelers. A working laboratory model of a new system of radar that makes use of a beam of light is said to be ten thousand times more accurate than the best comparable system of radar that used microwaves.The model has shown that this radar system, known as laser-doppler radar, can measure with absolute precision speeds varying from spaceship orbital injection (进入) velocities (速度) of five miles per second down to virtual stops—speeds of less than one ten thousandth of an inch per second. According to the scientists who are developing this system, such fine measures of velocity are of prime importance in space missions. In a rendezvous (对接) between two spaceships, or in a landing approach by a vehicle onto an orbiting space station, a bump could rip open a ship’s skin, or a nudge could knock the station out of its orbit.The light-beam radar, which operates at a frequency of trillions (百万兆) of cycles per second, could easily detect and measure the movement of a vehicle edging up to a satellite space station. A control system using so precise a signal as this would allow a huge vehicle to dock at a space station as lightly as a feather. Implied but not stated is that ()
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Have you ever been startled by a loud noise or by someone appearing suddenly behind you on dark night or by a snake in the grass Do you remember the sudden, tight feeling in your chest, the way your heart started go pound, the way you seemed to breathe more rapidly Such reactions occurred because you were frightened. Your brain sent a signal to the special gland (腺) in your body caned the adrenal (肾上的) gland. Other parts of your body were involved, too, but the adrenal gland has a very special function.The adrenal gland is located on top of your kidney. Since you have two kidneys. You also have two adrenal glands. Each adrenal gland is divided into two parts: a cortex (外皮) and a medulla (髓质). The cortex forms the outer shell; the medulla forms the central core. Both the cortex and the medulla secrete (分泌) hormones, but they have different functions.The cortex produces more than forty different chemical compounds and hormones. All these things are essential to sustain life. The medulla secretes adrenalin (also called epinephrine, the hormone that prepares the body for emergencies.)When you are suddenly faced with a dangerous or stressful situation, part of your brain instantly sends a signal to the adrenal gland, and all sorts of things begin to your body. The medulla releases an extra amount of adrenalin into the bloodstream. The adrenalin is carried rapidly throughout the body, stimulating other glands and systems. It is () that mainly helps you respond to a dangerous or stressful situation
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商业上常将CIF称作“到岸价”，也就是说，按CIF条件成交，卖方要承担货物运达目的港之前的一切风险、责任和费用。
Have you ever been startled by a loud noise or by someone appearing suddenly behind you on dark night or by a snake in the grass Do you remember the sudden, tight feeling in your chest, the way your heart started go pound, the way you seemed to breathe more rapidly Such reactions occurred because you were frightened. Your brain sent a signal to the special gland (腺) in your body caned the adrenal (肾上的) gland. Other parts of your body were involved, too, but the adrenal gland has a very special function.The adrenal gland is located on top of your kidney. Since you have two kidneys. You also have two adrenal glands. Each adrenal gland is divided into two parts: a cortex (外皮) and a medulla (髓质). The cortex forms the outer shell; the medulla forms the central core. Both the cortex and the medulla secrete (分泌) hormones, but they have different functions.The cortex produces more than forty different chemical compounds and hormones. All these things are essential to sustain life. The medulla secretes adrenalin (also called epinephrine, the hormone that prepares the body for emergencies.)When you are suddenly faced with a dangerous or stressful situation, part of your brain instantly sends a signal to the adrenal gland, and all sorts of things begin to your body. The medulla releases an extra amount of adrenalin into the bloodstream. The adrenalin is carried rapidly throughout the body, stimulating other glands and systems. What could be said about the adrenalin()
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