John Ternus became Apple’s chief executive on Tuesday, succeeding Tim Cook, the company’s leader for the last 15 years. The long-anticipated handoff, Mr. Cook has said, will be “perfectly smooth.” 约翰·特纳斯于周二正式成为苹果公司首席执行官，接替了过去15年一直领导该公司的蒂姆·库克。库克曾表示，这场备受期待的权力交接将“无比顺利”。…