Chinese Premier Wen Jiabao will meet here Wednesday with US President Barack Obama, who is on his first state visit to China since his January inauguration.     They will have a working lunch before Obama's sightseeing visit to the Great Wall in the north suburb of the Chinese capital, which will be another chance for the US head of state, who toured the Imperial Palace Tuesday, to learn more about the ancient Chinese civilization.     Obama will conclude his fist visit to China and fly to the Republic of Korea, the last leg of his four-state Asian tour, in the afternoon.     He arrived in China's economic hub Shanghai Sunday night to kick off this visit as guest of his Chinese counterpart Hu Jintao.     Hu held talks with him in Beijing on Tuesday and they met international reporters for about 40 minutes after the talks, both pledging to further bilateral ties.     Top Chinese legislator Wu Bangguo also met Obama on Tuesday, several hours before a state banquet in the Great Hall of the People in downtown Beijing.     In a joint statement issued on Tuesday, the two sides spoke highly of the tremendous development achieved since the two countries established diplomatic relations 30 years ago and reached consensus on further bilateral ties.