SHANGHAI, March 15, 2012 (Xinhua) -- Staff members hold advertisement board of houses during a bussiness promotion of "2012 Spring in Shanghai" real estate trade fair in Shanghai, capital of China, March 15, 2012. The four-day real estate trade fair, which is considered as a vane of the real estate market in Shanghai, kicked off here with 60 exhibitors from home and abroad. (Xinhua/Niu Yixin)