由于润滑油的循环流动,可以带走摩擦表面所产生的部分热量,对机件产生什么作用() A.

题型:单项选择题

问题:

由于润滑油的循环流动,可以带走摩擦表面所产生的部分热量,对机件产生什么作用()

A.降温

B.升温

C.保温

考点:场(厂)内专用机动车辆作业场(厂)内专用机动车辆作业题库
题型:单项选择题

It is good news that more and more people choose the bicycle as the means of transportation in China because there is too much traffic in the busy streets.

Xu Shima was 16 in 1980 and had to learn a trade(买卖). He c__小题1:___ bicycle repair. Over the next twenty years, it proved to be a wise d___小题2:__. At that time, China was known a___小题3:___ the "Kingdom of Bicycles" and was home to the world's largest number of people who ride bicycles. In the 1990s, Xu's business was the most s__小题4:__.

But in 2000, Xu had to g__小题5:___ up his trade because more and more people began to use electric bicycles and cars. He even made a living by s__小题6:___ fruits and working as a factory security guard (保安). He showed n___小题7:___ interest in returning to bicycle repair.

Yet the tide has again turned, and in 2009 Xu returned to his trade and now repairs a lot of bicycles a day. Xu is o___小题8:___ of 155 bike mechanics (修理工) at the Hangzhou Public Bicycle Transportation Development Co and fixes the company's n___小题9:___ 70,000 public bicycles in the city.

"I'm glad cycling is p___小题10:___ again," says Xu.

Inspired by the public bicycle system in Paris, Hangzhou government set up its own project in May 2008, hoping to ease the city's increasing traffic jams in this way.

题型:单项选择题
申请某种许可证,根据规定需要通过统一考试才能获得,且考试最多允许考四次.设X表示一位申请者经过考试的次数,据统计数据分析知X的概率分布如下:
X1234
P0.1x0.30.1
(Ⅰ)求一位申请者所经过的平均考试次数;
(Ⅱ)已知每名申请者参加X次考试需缴纳费用Y=100X+30(单位:元),求两位申请者所需费用的和小于500元的概率;
(Ⅲ)在(Ⅱ)的条件下,4位申请者中获得许可证的考试费用低于300元的人数记为ξ,求ξ的分布列.
题型:单项选择题

宫颈糜烂的病理,错误的是

A.鳞状上皮脱落后由柱状上皮覆盖
B.间质增生后呈颗粒状
C.间质继续增生、糜烂而呈乳突状
D."鳞状"是糜烂的愈合过程
E.糜烂是子宫颈炎症化脓的过程

题型:单项选择题

流体过渡流时的雷诺系数应为()。

A、Re≤2000

B、Re≥2000

C、Re≥4000

D、2000≤Re≤4000

题型:单项选择题

压缩机为什么不能带压启动和带压停车?

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