问题 选择题

一艘船若在静水中运动,其速度为4m/s,若它要渡过一条宽为40m的河,河水流速为3m/s,则下列说法错误的是(    )

A.这艘船无论如何也不能渡过这条河

B.这艘船相对于河岸的速度一定是5m/s

C.这艘船无法垂直于河岸渡河,并抵达正对岸

D.这艘船渡河的时间不可能少于10s

答案

ABC

题目分析:将小船的运动分解为沿河岸方向和垂直于河岸方向,分运动与合运动具有等时性,当静水速垂直于河岸时,渡河的时间最短.

解:A.这艘船一定可以渡河,A错误;

B.船在静水中运动的速度方向可以变化,这艘船相对于河岸的速度不一定是5m/s,B错误;

D.当静水速垂直于河岸时,渡河时间最短,最短时间,这艘船渡河的时间不可能少于10s,C错误,D正确.

故选:ABC.

点评:解决本题的关键将小船的运动分解为沿河岸方向和垂直于河岸方向,抓住分运动与合运动具有等时性,求出最短的渡河时间.

阅读理解

Three-point-four billion riders on New York City subways and buses a year. This amazing number equals one-third of all mass transit trips in the United States. Ridership is at its highest in almost 60 years in almost every American city.

A commuter advocacy group, “Straphangers Campaign,” attributes it to younger Americans, said Gene Russianoff.

“Millenials(千禧一代), those people born around the turn of the past century are much less car-oriented," he said. "They are urban. They like not owning cars, they like less responsibility and there are a lot of them."

In addition to millenials, many people believe public transit is economical and eco-friendly. In 2012 across America, people took 10.7 billion trips.

“When we talk about insurance rates going up, price of automobiles going up, then people are waking up and realizing: wait, here’s this huge asset(优点)that has been underutilized," said Richard Rudolph, chairman of the Rail Users Network. "Why not take advantage of this particular opportunity. It certainly makes more sense to get people out of automobiles into subways and into commuter and passenger railroads.”

New York is not standing still -- as passenger demand requires several major expansion projects. A new $4.5 billion subway line on New York’s Second Avenue -- which was recently excavated underneath businesses and apartment houses -- will take an overload of passengers off of other subway lines. Its first phase completion is scheduled in 2016.

People who work in New York’s financial district will soon be using a new transit subway transfer center. Almost all lines converge in lower Manhattan and the new center will give riders an easier way to get around the city and into New Jersey.

And, probably the most controversial and costly project is a $7 billion tunnel connection from Long Island into Manhattan’s Grand Central Terminal. Trains from there will have access to New York’s midtown business district.

Andrew Albert, a board member of the Metropolitan Transit Authority, said there were many other reasons the public was riding in increasing numbers.

“The system has gotten a lot more dependable. We have new cars. We have countdown clocks to tell you when the next train is coming. We have expanded facilities in places," he said.

New York’s 24-hour, 7-day-a-week, transit system costs a $1.5 billion a year to maintain. It is one of the world’s oldest, with its first subway line having opened in 1904.

小题1:Who is more likely to use public transmit?

A.People living in suburb          B.American young people     

B.People living in the countryside     D.American old people.

小题2:What does the underlined word in the 5th paragragh “underutilized” mean?

A.Not be put forward

B.not be noticed

C.not be made full use of

D.not be thought of小题3:What does the underlined sentence in the 6th paragragh “New York is not standing still” mean?

A.New York is taking action to expand public transmit.

B.New York will encourage more people to use public transmit.

C.New York will make public transmit faster.

D.New York is waking up and realizing the importance of public transmit.小题4:Which is Not the reason why the public is riding subways and buses in increasing numbers.

A.Public transport facilities are better than before.

B.Many people believe public transit is economical and eco-friendly.

C.The system has gotten a lot more dependable.

D.It is more convenient to ride city subways and buses.

填空题