Alexa needs a little work and bing is not helping. 

Try it yourself: 3/5

“Alexa, which United States presidents are still alive?”

“The US presidents that I know are alive are Barack Obama, George W. Bush, and Bill Clinton.”

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“Alexa, list the living U.S. Presidents.”

“Alive US Presidents include Donald Trump, Barack Obama, Jimmy Carter, Franklin D. Roosevelt, and Ronald Reagan.”