问题 解答题
某工厂仓库有一批钢条(称为原材料),每条长都是4.6米.现在要把它们锯成每根长0.7米和0.4米的甲、乙两种产品.
(1)试写出把每条原材料锯成甲、乙两种产品,恰好没有剩余残料的所有锯法:
方法编号甲产品根数乙产品根数
(2)如果该工厂要用11条原材料锯出根数相等的甲、乙两种产品,按上述无残料锯法的每种方法各锯的条数是:
方法编号应锯原材料条数
答案

(1)设锯成每根长0.7米的x根;0.4米的y根,则有0.7x+0.4y=4.6,

当x取1,2,3,4…去试探,发现只有当x=2时,y=8,

当x=6时,y=1两种锯法,

即可有两种分配方法使恰好没有剩余.

1、0.7米材料2根,0.4米8根;

2、0.7米材料6根,0.4米1根;

如图:

(2)因为11条原材料锯出根数相等的甲、乙两种产品,

可以根据上面的分配方法,把5根原材料按每根锯0.7米材料2根,0.4米8根;

6根原材料按每根锯0.7米材料6根,0.4米1根;

即可得出46根0.7米和46根0.4米的甲、乙两种产品.

阅读理解

阅读理解

     In Britain, in a population of 60 million, there are 13 million grandparents, many of whom live alone a

long way from their grandchildren.The loneliness of these older people has become an issue that schools

are trying to teach children about .

     On a popular teacher's website, there is a classroom activity to help make children aware of the

implications of the different generations of the same family living far from each other. It's a story about Mrs. Eiderdown, an elderly lady whose grandchildren have moved to Australia with their parents. She lives

alone and rarely sees her family .

     First of all, the children speculate about Mrs. Eiderdown's life.  What does she have for breakfast ?

what does she do all day ?how does she feel about her life ?

     One day, Mrs. Eiderdown decides that she wants a pet to keep her company and puts an

advertisement in a local shop window. Then she waits at home to see if anyone will answer her

advertisement .

     A tall thin man rings her doorbell. he is holding a cardboard box. Mrs. Eiderdown chats with the man

for ten minutes before she realizes that she hasn't looked in-side the box to see what the pet is. She can hear a his-sing sound. The children guess what is in the box(a snake). Mrs. Eiderdown thanks the man but

says she doesn't think the snake is a good idea .

     The next time the doorbell rings, there's a lady on the doorstep, also carrying a cardboard box.In the

bottom of the box, Mrs. Eiderdown sees something black and hairy with eight legs. Again ,the children say what they  think it is (a spider). Mrs. Eiderdown thanks the lady for her kindness but says that a spider is

not the sort of pet she has in mind.

At last, the little girl next door brings her a dog .Mrs. Eiderdown's life improves a lot because of the dog.

more importantly, of course, the little girl, whose own granny lives a long way away, starts to visit

Mrs.Eiderdown more often. This interactive classroom idea has led to a greater awareness among children about the possible loneliness of older people who live quite near them .

1.what's the main idea of the passage?

A.children get to know about the trouble of the elderly

B. neighbors help select pets for Mrs. Eiderdown

C. society helps the lonely people in the UK

D. school send pets to the lonely elderly

2.what does the underlined sentence in the third paragraph mean ?

A. they talk about how she feels about being old

B. they try to experience her loneliness

C. they try to imagine how she lives

D. they write about her life story

3.  what can we infer from the passage ?

A. the little girl often visits her own granny

B. the people who offer pets are lady's neighbors

C. the farther the elderly live ,the lonelier they feel

D. the little girl begins to care more about Mrs. Eiderdown

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