介绍:
Freestanding brooms have nothing to do with time and date, but it's a result of a low center of gravity.
"The broom is wide at the bottom and at the right angle can be balanced,"
said Dr Becky Smethurst, an astrophysicist from the University of Oxford to BBC.
And the challenge was good at killing time for people who are idle at home because of the coronavirus.
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