问题 多选题

自卸式货车可以提高工作效率,如图所示.在车厢由水平位置逐渐抬起到一定高度且货物还未滑离车厢的过程中,货物所受车厢的支持力FN和摩擦力Ff都在变化.下列说法中正确的是(  )

A.FN逐渐减小

B.FN先减小后不变

C.Ff逐渐增大

D.Ff先增大后不变

答案

货物的受力如图所示,根据共点力平衡得,FN=mgcosθ,Ff=mgsinθ,θ增大,则FN减小,Ff增大.故A、C正确,B、D错误.

故选:AC.

阅读理解

It would be very exciting to be a reporter on a newspaper.As soon as a reporter’s boss gives him a story to write,the reporter is on the job.He keeps his mind on what he is going to do.He does not begin writing the story until he knows what he should find out.He must know why he should write the story.

At times a reporter must search hard to find all of the facts he needs for a story.The facts may not be right under his nose.To find the facts,he has to recognize important details.While gathering information for a story,he asks himself questions:Should I use this information? Is this an important fact?

A reporter writes the story as fast as he can,so it can go right away into the newspaper.The story also needs a headline,which tells very quickly what the news story is about and is printed bigger and blacker than the rest of the news story.

Every big newspaper has many reporters,because many stories are needed in the newspaper.Would you like to be one?

小题1:A reporter writes the story as fast as possible because       .

A.he wants it to go into the newspaper quickly

B.people prefer to buy today’s newspaper

C.he wants to have a rest

D.he is good at writing it小题2:Which statement is true according to the passage?

A.Being a reporter is a tiring job.

B.It is easy for a reporter to find the facts.

C.The headline must tell the details of the news story.

D.A reporter begins to write when knowing what he should find out.小题3:Which is the writer’s opinion?

A.A reporters boss is usually very hard to his men.

B.The job of a newspaper reporter is exciting but not easy.

C.Everyone can write a good news story.

D.No one likes to be a reporter.小题4:The passage is about       .

A.the job of a news reporter

B.big newspapers in the world

C.how to write the headline of all article

D.how to gather information for a news story

单项选择题