问题 单项选择题 A1/A2型题

盐酸四环素在酸性(pH=2以下)条件下,降解生成()

A.差向四环素

B.脱水四环素

C.异四环素

D.差向脱水四环素

E.氧四环素

答案

参考答案:B

解析:弱酸性(pH=2.0~6.0)条件下形成4-差向四环素;在酸性条件下(pH<2)脱水后生成脱水四环素;4-差向四环素可进一步脱水,形成差向脱水四环素。

阅读理解

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 (呼吁) to aid postwar

Greece had been so successful that 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 favorite 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 a 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 in Charity Shops.

B. Charity Shop: Its Origin & Development.

C. Charity Shop: Where You Buy to Donate.

D. The Public's Concern about Charity Shops.

单项选择题