File photo taken on Feb. 16, 2017 shows media reporters and tourists visiting giant panda Bao Bao to say goodbye as the panda will return to China at the Smithsonian National Zoo in Washington D.C., the United States. Exactly 40 years ago, Beijing and Washington officially established diplomatic relations, thus ending nearly three decades of isolation, hostility and even confrontation between two big countries with a combined population of over 1 billion, and resetting the course of history and international politics. Just like the "Ping-Pong Diplomacy" that marked a thaw in China-U.S. relations, the establishment of diplomatic ties was another wise and resolute decision made by then Chinese and American leaders with great political courage and far-reaching vision. In the past four decades, their successors have followed their footsteps, guiding the China-U.S. relationship through all complexities and difficulties to maintain a generally steady and smooth development. (Xinhua/Yin Bogu)