手提式泡沫灭火机使用时，一手提环，一手抓底边，把灭火机（）轻轻摇动几下，泡沫便会喷出

方程x²-2x+k=0中，当k______时，方程有两个相等的实数根．

物体所受的重力与它的质量______，表达式为 _________ ，一个质量是30kg的物体所受重力是 _____ ．一只熊猫的体重是490N，它的质量是_____．

阅读理解

     The days of elderly women doing nothing but cooking huge meals on holidays are gone. Enter the

Red Hat Society －a group holding the belief that old ladies should have fun.

     "My grandmothers didn't do anything but keep house and serve everybody. They were programmed

to do that," said Emily Cornette, head of a chapter of the 7-year-old Red Hat Society.

     While men have long spent their time fishing and playing golf, women have sometimes seemed to

become unnoticed as they age. But the generation now turning 50 is the baby boomers, and the same

people who refused their parents' way of being young are now trying a new way of growing old.

     If you take into consideration feminism(女权主义), a bit of spare money, and better health for most

elderly, the Red Hat Society looks almost inevitable(必然的). In this society, women over 50 wear red

hats and purple clothes, while the women under 50 wear pink hats and light purple clothing.

     "The organization took the idea from a poem by Jenny Joseph that begins: "When I am an old woman,

I shall wear purple. With a red hat which doesn't go," said Ellen Cooper, who founded the Red Hat

Society in 1998. When the ladies started to wear the red hats, they attracted lots of attention.

    "The point of this is that we need a rest from always doing something for someone else," Cooper said. "Women feel so ashamed and sorry when they do something for themselves." This is why chapters are

discouraged from raising money or doing anything useful. "We're a ladies' play group. It couldn't be more

simple," added Cooper's assistant Joe Heywood.

1. The underlined word "chapter" in paragraph 2 means __________.

A. one branch of an organization          

B. a written agreement of a club

C. one part of a collection of poems      

D. a period in a society's history of the baby boomers

2. The "baby boomers" are a group of people who       

A. have gradually become more noticeable                                

B. tried living a different life from their parents when they were young

C. are worried about getting old too quickly  

D. are enjoying a good life with plenty of money to spend

3. We can infer from the text that          .

A.  members of the Red Hat Society are interested in raising money for social work

B.  members of the Red Hat Society are programmers who can plan well for their future

C. members of the Red Hat Society believers in equality between men and women

D.  members of the Red Hat Society are good at cooking big meals and taking care of others

4. Who set up the Red Hat Society ?

A. Emily Cornette .

B. Jenny Joseph .   

C. Joe Heywood .

D. Ellen Cooper .  

5. Women join the Red Hat Society because          .

A. they want to earn much money.          

B. they would like to appear more attractive

C. they would like to have fun and live for themselves

D. they want to be more like their parents

心肌的自动节律性是如何产生的？影响因素有哪些？

图4-7中柱底轴向荷载轴向力设计值F=12000kN，承台混凝土C35，f_t=15700kPa，按《建筑桩基技术规范》(JGJ94-2008)验算承台斜截面的受剪承载力。

对A₁-A₁截面，其验算式与下列（）组数据较为接近。

A．V=3870kN<8501kN

B．V=4245kN<9985kN

C．V=4000kN<72534kN

D．V=4000kN<9985kN