如图为质量m=1×103kg的小汽车在水平公路上行驶的俯视图,轮胎与路面间的最大

题型:计算题

问题:

如图为质量m=1×103kg的小汽车在水平公路上行驶的俯视图,轮胎与路面间的最大静摩擦力f=8×103 N。汽车经过半径r=50m的弯路时

(1)(3分)设转弯时路面水平,则汽车转弯做圆周运动的向心力由什么力提供?

(2)(3分)若车转弯时的摩擦力恰好等于最大静摩擦力,此时车速的大小v=?

(3)(3分)如果车速达到90km/h,这辆车会不会发生侧滑?

考点:生活中的其他圆周运动
题型:计算题

液压控制阀可分为方向控制阀、()、流量控制阀三大类,

题型:计算题

One day, many years ago, when I was working as a psychologist(心理学家)in England, I brought David into my office. His face was pale and he looked at his own feet.

David lost his father when he was two years old and lived with his mother and grandfather ever since. But when he was 13 ,his grandfather died and his mother was killed in a car accident. His teacher told me that he refused to talk to others form then on.

David didn’t say a word. As he was leaving, I put my hand on his shoulder.“Come back next week if you like.” I said.

He came and I suggested(建议)we play a game of chess. He agreed. After that we played chess every Wednesday afternoon—in complete silence. Usually, he arrived earlier than we agreed. It seemed that he liked to be with me.

Months later, when I was looking at his head, he suddenly looked up at me. “It’s your turn.” He said. After that day, David started started talking. He finally got friends in school and he even joined a bicycle club. Now he started his new life.

Maybe I gave David something. But I learned more from him. I learned that time makes it possible to get over what seems to be painful. David showed me how to help people like him.

小题1: When David came into the writer’s office,     .

A.he said hello to the writer

B.he seemed happy

C.he looked at his own feet

D.he smiled at the writer小题2: David’s father died when he was   year old.

A.13

B.2

C.5

D.6小题3: To help David, the writer   every Wednesday afternoon.

A.played chess with him

B.told stories to him

C.wrote letters to him

D.played soccer with him小题4: What club did David join?

A.chess club.

B.An art club.

C.An English club.

D.A bicycle club.小题5: Which of the following statements is NOT true?

A.After his father died, David refused to talk to others.

B.David didn’t say anything to the writer at first.

C.At last the writer learned a lot from David.

D.David finally got friends in school.

题型:计算题

位于睑板内的皮脂腺为()

A.Meibom腺

B.Zeiss腺

C.Kranse腺

D.以上都不是

E.Moll腺

题型:计算题

销售促进功能

题型:计算题

下列选项中,体现了现金管理风险的事项有()。

A.管库人员单人出入库房,未严格执行库房管理制度

B.无核对解款出纳人员身份,导致调拨款冒领

C.无在监控下双人开箱清点现金

D.申领现金没有仔细核对预留印章是否相符,带来盗用风险

E.员工随意外泄现金调动计划,带来安全隐患

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