The threats to the health of astronauts in space are very different from ______ on earth.

A．ones

B．that

C．it

D．those

人工彩色砂、石粒是以各种不同目度(颗料)的______或______焙烧后经化学处理而制得各种色彩骨料，其外观晶莹光洁，色泽鲜艳夺目，颜色______。