美联社新闻一分钟 AP 2016-10-21（在线收听）

This is AP News Minute.

Hillary Clinton and Donald Trump are set to take the debate stage Wednesday night for one final prime time showdown in Los Vegas. Both candidates facing their own challenges with 20 days to go before the election. For Trump, the debate may be his last opportunity to turn the race around while Hillary needs to answer new rounds of questions about her authenticity and trustworthiness.

Multiple firefighters were injuried in an explosion in Oregon. Fire officials say the explosion occurred as utility workers and firefighters responded to reports of a damaged gas line in northwest Portland. 

Professors at 14 Pennsylvinia state universities went on strike Wednesday after both sides failed to reach an agreement on a new contract. This is the first strike in the system's 34 year history which affects more than 100,000 students.

And the birth of an 80 pounds endangered black rhino is being called an extremely significant event by Iowa's zoo officials. With less than a thousand existence, the zoo says the birth is part of the effort to try to reverse a long decline in the number of black rhinos.

Suzanne Yee Gaffney, The Associated Press with AP News Minute.