strength通常指體力或人、事物等擁有的實力。
例句：
1、His energy was unbounded and his patience inexhaustible.
他有無窮的精力和無限的耐心。
2、Plants produce sugars and starch to provide themselves with energy.
植物產生糖和淀粉來為自身提供能量。
3、Her decision to continue shows great strength of will.
她決心堅持下去，顯示出了很大的意志力。