如图所示,用滑轮组提起重6×104N的物体,若滑轮组的功率是2.5kW,机械效率

题型:计算题

问题:

如图所示,用滑轮组提起重6×104N的物体,若滑轮组的功率是2.5kW,机械效率为80%,要把物体匀速提高1m,求

(1)拉力F多大?

(2)需用多长的时间?

考点:滑轮(组)中拉力的计算功率的计算滑轮(组)的机械效率
题型:计算题

土的级配指标______不小于5,同时______等于1-3,称土样级配良好。

A.Ip

B.Cu

C.Cc

D.IL

题型:计算题

引起胎儿窘迫最常见的原因是

A.PIH

B.脐带脱垂

C.脐带先露

D.胎盘功能不良

E.羊水过少

题型:计算题

如图所示,质量分别为m和m0的两物体用细绳连接。在m0上施加一个竖直向上恒力F,使两物体从静止开始一起向上做匀加速直线运动,上升的高度为h。下列说法正确的是(   )

A.细绳拉力大小为-mg

B.物体系动能增加量为Fh

C.物体系处于失重状态

D.系统加速上升时,某时刻两物间细绳忽然断开,物体m随即做自由落体运动

题型:计算题

除杀虫以外,还可抑制杀灭药材微生物、抑制药材呼吸的是()

A.硫黄熏蒸法

B.磷化铝熏蒸法

C.氯化苦熏蒸法

D.氨水熏蒸

E.醋酸钠喷洒

题型:计算题

Passage Three

One of Microsoft’s cool people, is Patrick Blackburn. As a test manager for the Product Group, Blackburn’s job may sound routine; however, he says it’s anything but that.
"Most people ,think of software testing as a mundane task of punching the keyboard like a monkey, trying to break the program," Blackburn says. "Part of that is true, but we write software programs called Monkeys to do that for us so that we don’t have to hire real monkeys. Real monkeys are too difficult to manage and don’t usually pass the personal hygiene criteria !" In reality, Blackburn says, testing responsibilities are very technically challenging and often include complete development cycles of their own. He spends most of his time coming up with creative incentives to convince his team to believe in schedules for products that don’t yet exist, hiring great people to build p teams, and pounding on the products to find bugs before the customer sees them.
According to Blackburn, the most critical thing you can do to succeed at Microsoft is to focus on what you believe is important. "It’s easy to get overwhelmed with everything going on around you, so first and foremost you need to stay focused," he says. "What you focus on needs to be something you firmly believe in so that you’ll pursue it and defend your mission with a passion. "
He also thinks that one of the biggest differences between his co-workers at Microsoft and those at his former workplace is the sense of ownership and the impact on the business that everyone shares. "We hire people who tend to become personally attached to the products and the success of the company, and the environment really perpetuates this," Blackburn says. "It’s much easier to motivate a team at Microsoft than any other company I’ve been in. "
One of the most difficult parts of Blackburn’s job is staying ahead of the people who report to him. "Because there are so many smart people and technology is changing so quickly, it is a constant challenge to keep up," he says. "I hope that’s because I hire such great people!"
To succeed, Blackburn uses time management tactics and allocates a specific amount of time to education. "My personal goal is to spend at least 20 percent of my time learning new things through formal and informal methods. "

Patrick Blackburn thinks software testing is ______ .

A.a routine and mundane job

B.technically challenging

C.like a monkey punching keyboard

D.partly done by monkeys

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