偏心工件的车削方法有（）种。A.4 B.5 C.6 D.3

Mr and Mrs White had two sons and three daughters. One Sunday Mrs White said to her husband, “The children don’t have any lessons today, and you’re free too. There’s a new funfair(游乐场) in the park. Let’s all go there to play.”

Her husband said, “I want to finish some work today.” “Oh, forget it. Go there and make our children happy. That’s the most important work.” Mrs White said.

So Mr and Mrs White took their children to the funfair. Mr White was 45 years old, but he enjoyed the funfair more than his children. He hurried from one thing to another, and ate lots of sweets. One of his children said to his mother, “Dad is just like a small child, isn’t he, mom?” Mrs White didn’t want to follow his husband around any more at that time and answered, “He is even worse than a small child, Mary, because he might spend more money than a small child.”

小题1: There were_____ children in the family.

A．two

B．three

C．four

D．five小题2: One Sunday, Mrs and Mr White wanted to go to_____ with their children.

A．school

B．work

C．a funfair

D．a shop小题3: Mr White liked the place so much that he_____.

A．sold lots of sweets

B．followed his wife all the time

C．hurried from one thing to another

D．asked a lot of questions小题4: From the story we know Mrs White_____ when Mary asked her the question.

A．was still excited to play

B．was a little angry with Mr White

C．looked for Mr White everywhere

D．ate a lot of sweets小题5: Of all the family members, _____enjoyed playing there most that Sunday.

A．Mr White

B．Mrs White

C．Mary

D．the boys

某校高中生共有2700人，其中高一年级1000人，高二年级900人，高三年级800人，现采用分层抽样法抽取一个容量为81的样本，那么从高一、高二、高三各年级抽取人数分别为______．

正弦电压u的幅值为10V，其波形如图所示，施加于容抗X_C=5Ω的电容元件上，通过该元件的电流I_C与u取关联正方向，则电流I_C=()。

A．50sin(ωt-90°)A

B．2sin(ωt+120°)A

C．50sin(ωt+90°)A

D．2sin(ωt-120°)A

空压机使用润滑油应具备的条件之一是（）

A.一定高的闪点

B.低闪点

C.没有要求

葡萄发酵可产生葡萄酒，请利用相关的知识回答问题：

该微生物通过厌氧呼吸可分解（），产生的终产物是（）。