known substance

• 已知物,已知物质

known substance的用法和样例：

例句

1. Diamond is the hardest substance known.
   钻石是已知物质中最硬者。
2. But aerogel is able to slow the particles down to a halt within the space of a few dozen microns, and preserve them better than any known substance.
   但是气凝胶能够让这些颗粒减速并最终在几十微米的距离上停下来，比其他任何已知物质更好的保护它们。