有下列叙述：①整数a的倒数是1a；②因为4.8÷0.8=6，所以4.8能被0.8_爱下问搜题

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问题选择题

有下列叙述：①整数a的倒数是

1

a

；②因为4.8÷0.8=6，所以4.8能被0.8整除；③六年级一、二班共102人，全部到齐，出勤率102%；④一项工程由甲队单独做12天完成，乙队做9天完成，则甲、乙两队工作效率的比是12：9．其中错误的个数（　　）

A．1

B．2

C．3

D．4

答案

①整数a的倒数是

1

a

；

本题没有考虑到0的情况，0没有倒数；故本题错．

②因为4.8÷0.8=6，所以4.8能被0.8整除

整除的概念只存在于自然数中，4.8和0.8都是小数，故本题错．

③六年级一、二班共102人，全部到齐，出勤率102%；

出勤率是指出勤人数占总人数的百分比，其最大值为100%，故本题错．

④一项工程由甲队单独做12天完成，乙队做9天完成，则甲、乙两队工作效率的比是12：9．

把这项工程看成单位“1”，甲的工作效率是：

1

12

，乙的工作效率是

1

9

；

1

12

：

1

9

=9：12，故本题错．

错误的数量是4个；

故答案选：D．

实验题

某同学要测量一石块的密度。他按以下设计的步骤进行了实验：

A．在量筒中倒入适量的水，并记下水的体积V₁

B．将石块用细线系好后慢慢地放入量筒中（忽略细线的体积），并记下体积V₂

C．将石块从量筒中取出直接放到已经调好的天平上测得了石块的质量m

（1）由图可知，该同学测得的石块质量为___________g,体积为__________cm³,由此计算出石块的密度为__________kg/m³。

（2）按此步骤测得石块的密度值比真实值___________（选填“大”或“小”）。

原因是________ ___。

（3）步骤A中“适量的水”的含义是_________________________。

完形填空

A farmer had some puppies（小狗）to   36  . He painted a sign advertising the puppies and   37__ nailing （钉）it to a post on the edge of his yard. As he was driving the last nail into the post, a little boy came to him.
“Mister,” he said, “I want to buy one of your puppies.”
“Well,” said the farmer, as he   38  the sweat off his face, “these puppies come from fine parents and cost   39  money. Do you have enough money?”
The boy    40   his head for a moment. Then reaching into his pocket, he pulled out a handful of   41  and held it up to the farmer. “I’ve got thirty-nine cents. Is that enough to take a look?” “Sure,” said the farmer. And with that he  42  a whistle (口哨声), “Here, Dolly!” he called.   43  from the doghouse and down the ramp ran Dolly    44  by four little balls of fur. The little boy’ eyes danced with delight. As the dogs made their   45  to the fence, the little boy noticed something else stirring inside the doghouse.   46    another little ball appeared; this one noticeably smaller. Then in a somewhat    47   manner the little pup began hobbling（蹒跚） toward the others, doing its best to    48  .
“I want that one,” the little boy said,   49   to the smallest one. The farmer said, “Son, you don’t want that puppy. He will never be able to run and play with you   50  these other dogs would.”
With that the little boy   51  back from the fence, and began    52    up one leg of his trousers. In doing so he exposed a steel support running down both sides of his leg   53  itself to a specially made   54   . Looking back up at the farmer, he said, “You see sir, I don't   55   too well myself, and he will need someone who understands.”

A．a number of

B．quite a few

C．a great deal of

D．only a little

C．being attached