Here are a few things to know about the day’s nonvirus news from The Associated Press. Ohio’s primary will be the nation’s first major test of an almost fully mail-in balloting contest. Kim Jong Un’s disappearance from the public view shows the disconnect between curiosity about what’s happening inside North Korea and the secrecy surrounding its leadership. The National Transportation Safety Board will release the results of an investigation into the sinking of an amphibious duck boat in Missouri in 2018 that killed 17 of the 31 passengers on board.