Administration of Taxation: individuals who transfer their purchased ordinary housing for over 2 years can enjoy zero tax

I have read the recent preferential policies about housing: in 2009, if individuals sell their ordinary housing which are bought for more than two years (including two years) , the exchange would be exempted
from sales tax.
I read a news the day of yesterday,the mayor of Beijing and Shanghai said that the price of housing is too high. I found that many people are capable to purchase their own apartment without any consuming for entirly 30 years.at the same time,some real estate businessmen and local officials said,they cann’t allow the price of house to fall down.
so I believe this is a good policy which can provide the more housing source for the ordinary people who want to buy their house and result in the decline of house price indirectly.