问题 解答题

某物流公司的甲、乙两辆货车分别从相距300千米的A、B两地同时出发相向而行,并以各自的速度匀速行驶,两车行驶1.5小时时甲车先到达配货站C地,此时两车相距30千米,甲车在C地用1小时配货,然后按原速度开往B地;乙车行驶2小时时也到C地,未停留继续开往A地。(友情提醒:画出线段图帮助分析)

(1)乙车的速度是______千米/小时,B、C两地的距离是______千米,A、C两地的距离是______千米;

(2)求甲车的速度及甲车到达B地所用的时间;

(3)乙车出发多长时间,两车相距150千米。

答案

解:(1)乙车的速度=30÷(2-1.5)=60千米/时;

B、C两地的距离=60×2=120千米;

A、C两地的距离=300-120=180千米;

故答案为60,120,180;

(2)甲车的速度=180÷1.5=120千米/小时;

甲车到达B地所用的时间=300÷120+1=3.5小时; 

 (3)设乙车出发x小时,两车相距150千米,

列方程得300-(60+120)x=150或60x+120(x-1)=300+150,

解得x=

即乙车出发小时,两车相距150千米。

选择题
阅读理解

Visitors from space may have landed on our planet from time to time, maybe hundreds of times during the long, empty ages while Man was still a dream of the far future. Indeed, they could have landed on 90% of the earth as recently as two or three hundreds years ago, and we could never have heard of it. If one searches through old newspapers and records from some certain places, one can find many reports of strange events that could be some explanations about visiting from outer space. A writer, Charles Fort, has made a collection of UFO sightings in his book Lo! One is tempted(引诱) to believe them more than any modern reports, for the simple reason that they happened long before anyone had ever thought of space travel. Yet at the same time, one cannot take them too seriously, for before education on science was popular, even sightings of meteors(流星) and comets(彗星) made people believe the most unbelievable stories, as they still do today.

56.小题1:According to the passage, visitors from outer space may have landed on the earth      .

A.long before man had dreamed of it

B.long before there were human beings

C.in the last few hundred years

D.after the space travel began57.小题2:Which of the following statements is true according to the passage?

A.Charles Fort sighted a lot of UFOs himself.

B.All sightings of UFOs are believable.

C.There may be living things on other planets.

D.People have seen visitors from other planets everywhere.58.小题3:According to the passage,           .

A.UFOs are only seen in recent years

B.UFOs sightings are not new

C.UFOs are just meteors and comets

D.UFOs are invented by people