【正确答案】 A

【答案解析】[解析] 22-25
Economics and weather have a lot in common．Knowing what conditions will be like weeks or months in the future is not easy．One thing that helps economists predict the future is the index of leading economic indicators．
An index is a way to measure changes in a group of numbers over time．In financial markets，for example，an index of stocks will rise or fall with changes in the wider market．The changes measured by an index can be represented with a single percentage．
The index may start at a base period oftime with a value ofone hundred．Now say that a month later the value is recorded as one hundred and one．That means it gained one percent．If the index lost one percent,however,the value would be ninety-nine．
The leading economic indicators are really ten indexes．Four deal with manufacturing activity；one deals with unemployment claims；another measures people's expectations of the economy；still others involve financial information like the money supply and interest rates．
The index of leading indicators is just one of the tools used to measure the business cycle．Business cycles are the normal changes that happen in economic growth over time．
A measure called the coincident index provides information about current conditions．Employment rotes are all important part of it．There is also a lagging index．It helps confirm economic changes that currently appear to be taking place． Interest rates are an important lagging indicator．

22．What's an index according to the passage7

[解析] 选A，信息明示题。文章指出，指数是测量一定时间内一组数字的变化的方法，故选A。

【正确答案】 D

【答案解析】[解析]
What would the value be if the index lost twenty-one percent?

[解析] 选D，综合推断题。文章指出，如果数值为101，就说明指数涨了1个百分点：如果指数减少1个百分点，数值就是99。由此可知，如果指数减少21个百分点，那么数值就是79。

【正确答案】 B

【答案解析】[解析]
How many indexes are there measuring financial information?

[解析] 选B，综合推断题。文章指出，10个经济指数中有4个与制造业有关，1个与失业统计有关，1个用于测量人们对经济的期望值，其余的与金融信息有关，由此可知，用于衡量金融信息的指数应该有4个(10-4-1-1=4)。

【正确答案】 A

【答案解析】[解析]
What can we learn about the coincident index according to the passage?

[解析] 选A，信息明示题。文章最后指出，重合指数可以提供当前情况的信息，故选A。就业率是重合指数的重要组成部分，由此可排除D；帮助确定即将可能发生的经济变化的是后续指数，而利率是重要的后续指数．由此可排除B、C。