Rain and frost are naturalagents that wear away rocks.
雨和霜都是磨蚀岩石的自然力。
2
Therefore the calcium and magnesium together are the naturalagents for relaxation and calmness.
钙和镁并用，成为天然的放松剂和镇静剂。
3
It will be seen hereafter how much of the economy of society depends on the limited quantity in which some of the most important naturalagents exist, and more particularly land.