台湾籍旅美老师今天交给我们的句子是：
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.
事实上，和硬币一样直径的黑洞其质量比地球还稍稍重一些，它的表重力，比我们现在的星球还大上数百亿倍。
