China was confident of holding a "successful, wonderful and impressive World Expo" after further improvements on facilities, services and managements following the trial runs.

Problems exposed during the six trial runs, between April 20 and April 26, were corrected and services were improved, Yang Xiong, member of the Shanghai World Expo organizing committee, said at a press conference Wednesday.

More volunteers and public facilities, including chairs, wheel chairs and garbage cans, were added in the Expo park, while 88 temporary food sale booths were planned and traveling food stores would be added when necessary, said Yang, also executive deputy mayor of Shanghai.

Food prices at the Expo park saw a decline after organizers working to cut sellers' operating costs and enhancing price monitoring, he said.

However, the trial runs were only "warm-ups", "we will face the real challenges during the 184-day operation after the opening," he said.

The Shanghai World Expo, scheduled to open on May 1, will last six months. It will be the largest world exhibition ever and is expected to attract 70 million visitors from both home and abroad.