Alibaba Group Holding Ltd. co-founder Jack Ma has joined Twitter. In his first-tweet, Ma posted photos of a China-Eastern-Airlines-plane with boxes of coronavirus test kits and face masks slated to be shipped and donated to the U.S. from Shanghai. "All the best to our friends in America," he wrote, which garnered more than 3,500 retweets and 20,000 likes in the first hour after posting.