他采集了各种岩石和矿物的样品.He collected specimens of all kinds of rocks and minerals.硅酸盐矿物的特点是耐熔和难以分离.Silicate minerals are characteristically refractory and difficult to break down.此硬度计的依据是矿物的相对研磨能力.This scale is based on the relat...
Precautions had to be taken to prevent pilfering.必须采取防范措施阻止偷盗行为。You must take all reasonable precautions to protect yourself and your family.你必须采取一切合理的预防措施，保护自己和家人。The Danes had selfconfidence of conquerors, and their se...