问题 问答题 简答题

简述分级效率及其意义。

答案

参考答案:

综合分级效率εf反映了产物在质(纯度)、量(回收率)两方面提高的幅度。εf被定义为:实际被有效分级的细颗粒量P与理想条件下被分离的细颗粒量P0之比,用百分数表示。

式中第一项是细粒级产品中细粒的回收率,第二项是粗粒在细粒级产品中的回收率。可见,综合分级效率εf也可以说是细粒级产品中细粒的回收率与细粒级产品中粗粒回收率的差值。

细粒级产品中粗粒的回收率表示粗颗粒的混入对溢流产物质量降低的影响。

阅读理解

阅读理解

     When Mary Moore began her high school in 1951, her mother told her, "Be sure and take a typing

course so when this show business thing doesn't work out, you'll have something to rely on." Mary

responded in typical teenage fashion.From that moment on, "the very last thing I ever thought about

doing was taking a typing course, " she recalls.

     The show business thing worked out, of course.In her career, Mary won many awards.Only recently, when she began to write Growing Up Again, did she regret ignoring her mom, "I don't know how to

use a computer, " she admits.

     Unlike her 1995 autobiography, After All, her second book is less about life as an awardwinning

actress and more about living with diabetes (糖尿病). All the money from the book is intended for the

Juvenile Diabetes Research Foundation (JDRF), an organization she serves as international chairman. "I

felt there was a need for a book like this, " she says. "I didn't want to lecture, but I wanted other diabetics

to know that things get better when we're selfcontrolled and do our part in managing the disease."

     But she hasn't always practiced what she teaches.In her book, she describes that awful day, almost

40 years ago, when she received two pieces of lifechanging news.First, she had lost the baby she was

carrying, and second, tests showed that she had diabetes.In a childlike act, she left the hospital and

treated herself to a box of doughnuts (甜甜圈). Years would pass before she realized she had to grow

up-again-and take control of her diabetes, not let it control her.Only then did she kick her threepackaday

cigarette habit, overcome her addiction to alcohol, and begin to follow a balanced diet.

     Although her disease has affected her eyesight and forced her to the sidelines of the dance floor, she

refuses to fall into selfpity. "Everybody on earth can ask 'why me?' about something or other, " she insists. "It doesn't do any good.No one is immune (免疫的) to heartache, pain, and disappointments.Sometimes we can make things better by helping others.I've come to realize the importance of that as I've grown up

this second time.I want to speak out and be as helpful as I can be."

1. Why did Mary feel regretful?

A. She didn't achieve her ambition.

B. She didn't take care of her mother.

C. She didn't complete her high school.

D. She didn't follow her mother's advice.

2. We can know that before 1995 Mary ________.

A. had two books published

B. received many career awards

C. knew how to use a computer

D. supported the JDRF by writing

3. Mary's second book Growing Up Again is mainly about her ________.

A. living with diabetes

B. successful show business

C. service for an organization

D. remembrance of her mother

4. When Mary received the lifechanging news, she ________.

A. lost control of herself

B. began a balanced diet

C. tried to get a treatment

D. behaved in an adult way

5. What can we know from the last paragraph?

A. Mary feels pity for herself.

B. Mary has recovered from her disease.

C. Mary wants to help others as much as possible.

D. Mary determines to go back to the dance floor.

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