搜题请搜索小程序“爱下问搜题”
问题 填空题

身高1.65m的人，站在平面镜前3m处，则人在镜中的像与人的距离为______m．像高为______m，当人向平面镜走近时，人在镜中所成像的大小______（选填“变大”、“不变”或“变小”）．

答案

因为平面镜所成的像和物体各对应点到平面镜间距离相等，所以，由他到平面镜的距离为3m可得镜中所成的像与平面镜之间的距离为3m，则人与像之间的距离为3m+3m=6m；

由他身高1.65m可得镜中的像高也是1.65m；

因为平面镜所成的像和物体形状、大小相同，所以当人远离平面镜时，镜中像的大小将不会改变．

故答案为：6；1.65；不变．

单项选择题

处理落道事故，根据情况可采用（）上道。

A、绞车牵引

B、长柄工具

C、千斤或顶溜器

D、导链
查看答案
单项选择题

Passage One


It is quite reasonable to blame traffic jams, the cost of" gas and the great speed of modern life, but manners on the toad are becoming horrible. Eye,body knows that the nicest men would become fierce tigers behind the wheel. It is all right to have a tiger in a cage, but to have one in the driver’s seat is another matter.
Road politeness is not only good manners, but good sense too. It takes the most cool-headed drivers great patience to give up the desire to beat back when forced to face rude driving. On the other hand, a little politeness goes a long way towards reducing the possibility of quarrelling and fighting. A friendly nod or a wave of thanks in answer to an act of politeness helps to create an atmosphere of good will and calmness so necessary in modern traffic conditions. But such behaviors of politeness are by no means enough. Many drivers nowadays don’t even seem able to recognize politeness when they see it.
However, misplaced politeness can also be dangerous. Typical examples are the driver who waves a child crossing the street at a wrong place into the path of oncoming cars that may be not able to stop in time. The same goes for encouraging old ladies to cross the road wherever and whenever they want to.
An experienced driver, whose manners are faultless, told me it would help if drivers learnt to correctly join in traffic stream without causing total blockages that give rise to unpleasant feelings. Unfortunately, modern drivers can’t even learn to drive,let alone master the roadmanship. Years ago, experts warned us that the fast increase of the car ownership would demand more give-and-take from all road users. It is high time for all of us to take this message to heart.

Troubles on the road are often caused by______.

A．traffic jams

B．the behavior of the drivers

C．great speed

D．terrible road conditions
查看答案