问题 选择题

某品牌牙膏中的摩擦剂是经过一系列加工而制得的极细小的碳酸钙粉末,它的生产过程如下:

(1)请写出A物质的名称           (或化学式)

(2)请从①②③三个反应中选择一个,写出反应的化学方程式                     

(3)二氧化碳有许多用途,请举出其中一例                          

答案

(1) 氢氧化钙(或熟石灰:Ca(OH)2)

(2)  CaCO3 CaO + CO2↑ 

(或CaO + H2O ="=" Ca(OH)2;Ca(OH)2 + CO2 ="=" CaCO3↓+ H2O )

作灭火剂(或制干冰:在温室里作肥料等)

(1),生石灰与水反应生成氢氧化钙。(2)三个反应分别为CaCO3 CaO + CO2↑ ,CaO + H2O ="=" Ca(OH)2,Ca(OH)2 + CO2 ="=" CaCO3↓+ H2O

单项选择题
阅读理解

Credit cards let people buy things now and pay for them over months or even years.But some people get deep into debt:Some banks have terms and charges that can make it harder for people to pay off that debt.In the United States,there are calls for stronger government supervision of the credit card industry.They_offer_economic_power_at_a_price.In 2004,Americans had about $800 billion in credit card debt.Now they own about $968 billion.

Critics say banks made it too easy to get credit cards.But that may be changing.The crisis in the housing and credit they call markets is beginning to affect the credit card industry.More payments are late.Charges for late payments are a growing source of profit for banks.But late payments can also signal bad debts.

The central bank,the Federal Reserve,says two­thirds of American banks have recently reported tighter lending requirements.Many people report having their credit limits reduced without warning.

Some lawmakers are concerned that cardholders do not have enough protections from what abusive policies.These include actions like raising interest rates because of an unrelated event.Also,banks may raise the chances of a late payment by changing monthly payment dates for credit cards.

According to a survey,82% of Americans think credit cards provide a valuable service.But a majority,58%,say they do not trust credit card companies.And three out of four think the government should regulate the industry more closely.Three out of four people feel there is always some condition that makes a card less appealing than the company made in scared.And a little more than half say they have had a card that was not as good as they expected.But close to 80% say no one really reads the terms and conditions when they sign up for a credit card.

小题1:What does the underlined sentence in the first paragraph probably mean?

A.We can enjoy more convenience using credit cards.

B.Credit cards can improve our buying power.

C.We can buy things at lower prices using credit cards.

D.Credit cards bring more card debt as well as convenience.小题2:Which of the following is NOT mentioned in the text?

A.Banks are making it harder for people to get credit cards.

B.Some people’s credit limits have been reduced.

C.It is more difficult to borrow money from some banks.

D.Banks are receiving more charges from late payments.小题3:What can we know from the text?

A.Banks actually prefer to see more late payment.

B.People should be more careful when applying for a credit card.

C.The US government provides better protection for cardholders.

D.The majority of Americans don’t think much of credit cards.小题4:What is the main idea of the last paragraph?

A.Credit cards are still very well received in America.

B.Credit cards don’t live up to some people’s expectations.

C.Many people don’t believe in credit card companies.

D.The results of a survey about credit cards in Americans.