U.S. oil price turning negative represents a great trial/ 首现负油价，原油市场面临大考

A man wearing a face mask passes by gas pumps at a gas station in the Brooklyn borough of New York, the United States, April 20, 2020. /Xinhua

West Texas Intermediate (WTI) crude oil futures prices reached an alarmingly negative level for the first time. On April 21, Beijing time, the settlement...