“兆吨”用英语怎么说？

这颗彗星重约500兆吨, 面积相当于纽约市大小.The comet, weighing about 500 trillion tons, area equivalent to the size of New York City.话外音: 一百兆吨的尘石被抛入大气层.Voice: One hundred trillion tons of dirt and rock hurled into the atmosphere....