A:质量数为19,电子数为9
B:质子数为9,中子数为10
C:质子数为9,电子数为9
D:中子数为10,电子数为8
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6×3=____ 1×6=____ 6×4=____ 6×2=____ 6×6=____
—Look! There are two policemen.
—Yeah. They're walking us.