什么是渐变型多模光纤自聚焦效应？_爱下问搜题

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问题问答题简答题

什么是渐变型多模光纤自聚焦效应？

答案

参考答案：

不同入射角相应的光线，虽然经历的路程不同，但是最终都会聚在同一点上，这种现象称为自聚焦(Self Focusing)效应。

完形填空

Most people in the world like to enjoy nature. Travel is one of the most popular ways. Nowadays modern transportation can take people everywhere. But people who lived before the 1880s probably would not travel very far. They would not have time to travel far from their work. Anyone who travelled 36 would usually walk or ride a horse. But in Germany a man named Karl Benz had an idea that 37 the world in a dramatic way. In 1885, he made 38 . His car had three wheels, 39 most cars today. The car could only go 40 16 kilometres an hour.
At around the same time, the man 41 his first car in Detroit, America is called Henry Ford. Detroit is now still famous all over the world as the centre of American car-making.
Cars were very few and only 42 people could buy them. 43 , in England cars were thought to be 44 at that time, so for a few years someone 45 walk in front of every car 46 a red flag! This was to make sure that the car did not go too fast and hurt 47 .
In the 1910s, Henry Ford had 48 a better kind of car called the Model T Ford and he built a 49 where the cars could be made 50 . In this way the car could be made 51 and the cost was less and more and more people could 52 them. But there was still a problem 53 all the cars were black. That was because it was 54 to produce cars that were all the same color. Now, of course, you can buy cars in all 55 .

A．a first car

B．the first car

C．his first wheel

D．a first wheel

A．with a speed of

B．at a speed of

C．at speed of

D．for a speed of

D．having made

A．interesting

B．was forced to

A．with machine

B．by machines

D．using hands

单项选择题

肾性骨营养不良最常见和最主要的类型是（）

A.软骨病

B.骨硬化

C.纤维性骨炎

D.骨质疏松

E.营养不良和低蛋白血症