It's a common retort among those who have to work with President Trump but don't appreciate his tweeting: The president can do two things at once. Trump allies' argument goes like this: “The fact of the matter is that he can do more than one thing at a time,” Health and Human Services Secretary Tom Price said on NBC's “Meet the Press” on Sunday. That's technically true. The president can send a tweet while he's in a meeting. He could probably send several. It takes all of a couple seconds — a couple minutes, max — to formulate and post...