度娘虽然有时比较没节操，这点还是可以应付的。表示您上的是搜索引擎旗下的贴吧，有词典和搜索就在那儿。
Real size 和 Price level 的关系与区别。考试一般来说是不会直接来一个问题考你：“解释一下两者概念”的。

An economic expansion is an increase in the level of economic activity, and of the goods and services available in the market place. It is a period of economic growth as measured by a rise in real GDP.
Inflation is a rise in the general level of prices of goods and services in an economy over a period of time.When the general price level rises, each unit of currency buys fewer goods and services. Consequently, inflation also reflects an erosion in the purchasing power of money.