20150920【每日口說練習】(gravity)

In fact,
a black hole with the diameter of a nickel
would be slightly
more massive than the Earth.
It would have a surface gravity
a billion billion times greater than
our planet currently does.

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diameter
The gas meter reads 50.
Water was metered and charged for.
Measure the diameter of the circle.(radius)

nickel

gravity
zero gravity
specific gravity
center gravity
the law of gravity