CNN News:新冠肺炎仍有多个谜团待解

We are living in historic times. The events that we see worldwide today are the kind that appear in history books and encyclopedias in the decades to come. The big picture of how COVID-19 is infecting the world is still blurry. There's just so much that's still unknown about it.
There's no vaccine or universal treatment for the coronavirus, though scientists worldwide are racing to find them. It's not known exactly how it spreads or how long it stays on surfaces if they get contaminated. It's not known when exactly people are contagious once they've contracted it. And the symptoms range from severe and deadly to practically nothing.

But more details about this disease get filled in every day — where it's spreading, how many people are testing positive for it, where tests are available, which medications are showing some effectiveness in fighting it and which ones aren't, and how it's affecting industries, businesses, workers, parents and students.
When we put this show together, 92 percent of Americans were under stay-at-home orders. There were 11 states that didn't have them in place, but some of the local governments and counties within those states did.