活性污泥法运行过程中必须向处理系统供氧,这是因为()。 A.满足好氧微生物对溶解氧的

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问题:

活性污泥法运行过程中必须向处理系统供氧,这是因为()。

A.满足好氧微生物对溶解氧的需要

B.提高处理系统的效率

C.提高微生物的代谢活性

D.满足厌氧微生物对溶解氧的需要

考点:环保气象安全技能考试注册环保工程师(专业知识)注册环保工程师(专业知识)题库
题型:多项选择题

A few years ago, David had the idea of selling CDs over the Internet. He started his work from his home. Now he sells over 500,000 CDs a year and has made himself into a millionaire(百万富翁), at the age of 24.

“I could see that this was the future of shopping,” says David. “Why should you pay $15 for a CD and spend the time and the money going into the shop? You know sometimes you have to find a place for your car too. You can have the same CD for half of the price by clicking on your computer. And we can find any CD you want and bring it to your door in 24 hours!”

David said this is the only beginning, “One day we’ll do our shopping over the Internet: it’s easier, quicker and cheaper. Shops and supermarkets will be the past.”

小题1:How has he become a millionaire?

A.By making new supermarkets.

B.By making advertisements.

C.By selling ideas to others.

D.By selling CDs on the Internet.小题2:If you pay $15 for a CD in the shop, how much should you pay for it on the Internet?

A.$15.

B.$12.

C.$7.5.

D.$30.小题3:By shopping on the Internet, you won’t ________.

A.spend any time or money

B.drive your car any more

C.click on your computer

D.get into the shop by yourself小题4:What can we learn from the passage?

A.More than half of the people like to shop on the Internet.

B.Shops and supermarkets will be the past in the future.

C.Some people don’t like to go shopping over the Internet.

D.It’s easier, quicker and more expensive to do our shopping over the net.

题型:多项选择题

如图所示是建筑工地常用的一种“深穴打夯机”.工作时,电动机带动两个紧压夯杆的滚轮匀速运转将夯杆从深为h的坑中提上来,当两个滚轮彼此分开时,夯杆被释放,最后夯杆在自身的重力作用下,落回深坑夯实坑底.然后,两个滚轮再次压紧夯杆,夯杆再次被提上来,如此周而复始工作.已知两个滚轮的半径为R=40cm,角速度ω=10rad/s,每个滚轮对夯杆的正压力FN=2×104 N,滚轮与夯杆的动摩擦因数µ=0.3,夯杆质量m=1×103 kg,坑深h=6.4m.假定在打夯的过程中坑的深度不变,且夯杆底端刚到坑口时,速度恰好为零.取g=10m/s2

2
=1.4.求:

(1)夯杆上升过程中被滚轮释放时的速度为多大;此时夯杆底端离坑底多高;

(2)每次打夯的周期为多少.

题型:多项选择题

感觉训练的次序为()

A.保护觉训练、定位觉训练、形状觉训练、织物觉训练

B.保护觉训练、形状觉训练、定位觉训练、织物觉训练

C.保护觉训练、形状觉训练、织物觉训练、定位觉训练

D.保护觉训练、定位觉训练、织物觉训练、形状觉训练

E.保护觉训练、织物觉训练、定位觉训练、形状觉训练

题型:多项选择题

简述原料糖性质。

题型:多项选择题

某企业购买一幢单独建造的地下建筑物用于存放货物,于2016年8月2日签署合同,在8月15日取得了地下建筑物产权证书及土地使用证书,注明土地面积400平方米,当地城镇土地使用税单位年税额为每平方米12元,则该企业2016年应纳的城镇土地使用税是()元。

A.800

B.1000

C.1800

D.2400

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