进行悬浮物固体含量分析时，采用的滤膜孔径为（）。A、0.45μm B、0.5μm C

标准麻花钻在刃磨后角时，将主切削刃上各点的后角磨成外缘处小，接近中心处大，有什么好处

There seems never to have been a civilization without toys, but when and how they developed is unknown. They probably came about just to give children something to do .

In the ancient world , as is today ,most boys played with some kinds of toys and most girls with another .In societies where social roles are rigidly determined, boys pattern their play after the activities of their fathers and girls are being prepared, even in play , to step into the roles and responsibilities of the adult world .

What is remarkable about the history of toys is not so much how they changed over the centuries but how much they have remained the same . The changes have been mostly in terms of craftsmanship ,mechanics, and technology . It is the universality of toys with regard to their development in all parts of the world and their persistence to the present that is amazing .In Egypt ,America ,China ,Japan and among the Arctic (北极的)people, generally the same kinds of toys appeared. Variations depended on local customs and way of life because toys imitate their surrounding. Nearly every civilization had dolls, little weapons, toy soldiers, tiny animals and vehicles.

Because toys can be generally regarded as a kind of art form, they have not been subject to technological leaps that characterize inventions for adult use .The progress from the wheel to the cart to the automobile is a direct line of ways up. The progress from a rattle (拔浪鼓) used by a baby in 3000BCto one used by an infant today , however , is not characterized by inventiveness. Each rattle is the product of the artistic tastes of the times and subject to the limitations of available materials.

小题1:The reason why the toys most boys play with are different from those that girls play with is that       .

A．their social roles are rigidly determined

B．they like challenging activities

C．most boys would like to follow their fathers’ professions

D．boys like to play with their fathers while girls with their mothers.小题2:One aspect of “the universality of toys ”lies in the fact that          .

A．the basic characteristics of toys are the same all over the world

B．technological advances have greatly improved the durability of toys

C．the exploration of the universe has led to the creation of new kinds of toys

D．the improvement of craftsmanship in making toys depends on the efforts of universities小题3:Which of the following is the author’s view on the historical development of toys?

A．Toys are playing an increasingly important role in shaping a child’s character.

B．The toy industry has witnessed great leaps in technology in recent years.

C．The craftsmanship in toy-making has remained essentially unchanged.

D．Toys have remained basically the same all through the centuries.小题4:Regarded as a kind of art form, toys          .

A．reflect the pace of social progress

B．are not characterized by technological progress

C．follow a direct line of ascent

D．also appeal greatly to adults

竞标性施工组织设计的编制程序和步骤，除具有工程施工组织总设计的特性外，还具有（）特点

A.未知性

B.重复性

C.一次性

D.可变性

小车显示本身车号循环（）

A.等待指令

B.接收指令

C.停止指令

患者男性，49岁，腰部隐痛10年，头晕、头痛伴肉眼血尿6天，查体：血压170／110mmHg，腰部触诊及肾脏。尿常规蛋白（++），白细胞（+），红细胞（+++），血Cr209μmol／L，B超示双肾体积增大，有众多囊性液性暗区

对辅助诊断有意义的器官是（）

A.肝

B.肺

C.心

D.脾

E.胃