问题 单项选择题

工厂需要加工一批零件,甲单犯工作需要96个小时完成,乙需要90个小时、丙需要80个小时。现在按照第一天甲乙合作,第二天甲丙合作,第三天乙丙合作的顺序轮班工作,每天工作8小时,当全部零件完成时,甲工作了多少小时?

A.16 

B.24 

C.44 

D.32

答案

参考答案:D

解析:解析 设工程总量为三人所用时间的最小公倍数1440,则甲的每小时工作效率为15,乙为16,丙为18。设3天为一个周期,一个周期中共计完成工作量为:(31+33+34)×8=784,还剩下1440-784=656。第四天甲乙合作共完成(15+16)×8=248个,第五天甲丙合作共完成(15+18)×8=264个,还剩下656-248-264=144,第六天由乙丙完成。则甲共工作了4天,共计32小时,故正确答案为D。 考点:工程问题

阅读理解

“Everybody loves a bargain.” One person's useless, ugly, or broken object can be another person's bargain. That is why so many Americans do not throw things away. They put them outside their houses. They put on a “For Sale” sign. And, as simple as that, they have a yard sale.         

The sellers put a paid announcement(付费通告)in a local newspaper. It tells when and where the yard sale will take place. These sales are very popular during weekends in spring, summer, and autumn. Early in the morning, all the things to be sold are carried out of the house. Then they sit all day in the sunlight----like tired guests at a party----waiting for someone to take them home.

Just about anything can be sold at a yard sale. Sometimes, there are more clothes than anything else. Cooking equipment is also popular. So are old toys, tools, books, tables and chairs. Then there are objects called “white elephants”. A white elephant is something you think is extremely ugly or useless. It may be an electric light shaped like a fish. You feel a sharp pain whenever you look at it. To someone else, however, it might be a thing of beauty and joy.

Some people go to yard sales to find a special thing that they collect. It may be old toy trains, for example, or painting of dogs. Experts say more Americans are collecting old things now than ever before. Most people who go to yard sales, however, are not looking for anything special. They might buy an object simply because it costs so little. They enjoy negotiating(谈判) over prices, even if they really do not need the object. Later, they may hold their own yard to sell all the things they have bought.

小题1:What kind of things will go to a yard sale?

A.Cheap and ugly things.

B.Things people no longer use.

C.Things out of season.

D.Things of great value.小题2:A white elephant refers to _________.

A.something that can cause a feeling of pain

B.something disliked by the owners while appreciated by others

C.something sold at the lowest prices

D.a toy shaped like a fish小题3:Most people go to yard sales to________.

A.find valuable paintings

B.look for something special

C.find a bargain

D.kill their time小题4:Which of the following is NOT true about a yard sale?

A.It may not be held when the weather is very cold.

B.It can last for a whole day.

C.It is usually held with a party.

D.It is held outdoors.小题5:We can infer from the last paragraph that__________.

A.people may find something of great value on a yard sale

B.yard sales only attract those who have a low income

C.things on a yard sale can cost people a lot

D.most people don’t want to go to yard sales.

单项选择题 A1型题