BEIJING, Jan. 11 (Xinhua) -- As U.S. President Barack Obama bid farewell to the nation in a speech in his hometown of Chicago, the United States and China -- the world's two largest economies -- can now take a moment to ponder the development of their relationship over the last eight years.

During Obama's two terms, the China-U.S. relationship saw an increasing depth, breadth and frequency of engagement. Over the past several years, the United States and China have worked hand in hand to confront challenges in ties and effectively manage their differences.

The two sides have played a key role in promoting global economic growth, bringing a positive deal on the Iran nuclear issue through multilateral diplomatic efforts, coping with the Ebola epidemic in West Africa, and most notably, in promoting the international community's response to climate change.

They have also made progress in establishing a bilateral investment treaty, strengthening mutual trust between the two militaries and achieving some breakthroughs in cyber security cooperation.

However, the relationship between Washington and Beijing hasn't always been a bed of roses.

Thorny issues such as cyber security, Taiwan, Tibet and human rights flared up from time to time, putting a strain on their relations. Washington's rebalance to the Asia-Pacific, under which it plans to relocate a large part of its diplomatic and military resources to the region, is widely interpreted as targeting China.

If the past eight years offer any guide to the incoming administration of President-elect Donald Trump, who made unfounded claims against China during the general election last year, nurturing mutual trust and knowing where to draw the line are essential for the world's most important bilateral relationship.

Ties between China and the United States must be rooted in trust and respect, vibrant trade cooperation, and a firm belief that the two great powers can co-exist peacefully. World peace relies on their ability to do so.

For two individuals who desire a close friendship, honesty is a must. By the same token, if the United States wants to build a close and friendly relationship with China, it must know where to draw the line.

Trump's predecessors have done the right thing. Now the ball's in his court.