在某工程双代号网络计划中，如果以某关键节点为完成节点的工作有3项，则该3项工作(

下列关于栈的叙述中不正确的是( )。

A．在栈的两端都能插入或删除数据

B．在栈中只能从一端插入或删除数据

C．栈中的数据是先进后出

D．栈是一种特殊的线性表

阅读理解。

     I love charity (慈善) shops and so do lots of other people in Britain because you find quite a few of them

on every high street. The charity shop is a British institution, selling everything from clothes to electric goods,

all at very good prices. You can get things you won't find in the shops anymore. The thing I like best about

them is that your money is going to a good cause and not into the pockets of profit-driven companies, and you

are not damaging the planet, but finding a new home for unwanted goods.

     The first charity shop was opened in 1947 by Oxfam. The famous charity's appeal to aid postwar Greece

had been so successful it had been flooded with donations (捐赠物). They decided to set up a shop to sell

some of these donations to raise money for that appeal. Now there are over 7,000 charity shops in the UK. My

favourite charity shop in my hometown is the Red Cross shop, where I always find children's books, all 10 or

20 pence each.

     Most of the people working in the charity shops are volunteers, although there is often a manager who gets

paid. Over 90% of the goods in the charity shops are donated by the public. Every morning you see bags of

unwanted items outside the front of shops, although they don't encourage this, rather ask people to bring things

in when the shop is open.     

     The shops have very low running costs: all profits go to charity work. Charity shops raise more than ￡110

million a year, funding (资助) medical research, overseas aid, supporting sick and poor children, homeless and

disabled people, and much more. What better place to spend your money? You get something special for a very

good price and a good moral sense. You provide funds to a good cause and tread lightly on the environment.

1. The author loves the charity shop mainly because of ____.

A. its convenient location

B. its great variety of goods

C. its spirit of goodwill

D. its nice shopping environment

2. The first charity shop in the UK was set up to ____.

A. sell cheap products

B. deal with unwanted things

C. raise money for patients

D. help a foreign country

3. Which of the following is TRUE about charity shops?

A. The operating costs are very low.

B. The staff are usually well paid.

C. 90% of the donations are second-hand.

D. They are open twenty-four hours a day.

4. Which of the following may be the best title for the passage?

A. What to Buy a Charity Shops.

B. Charity Shop: Its Origin & Development.

C. Charity Shop: Where You Buy to Donate.

D. The Public's Concern about Charity Shops.

劳动力供给弹性是( )变动对工资率变动的反应程度。

A．劳动力供给

B．劳动力需求

C．劳动力供给量

D．劳动力需求量

简述微积分先驱数学家的贡献。

电焊时严禁借用金属管道、金属脚手架、结构钢筋等金属物搭接代替（）使用。

A.导线

B.相线

C.零线

D.地线