ample 指不仅能达到应有的程度,满足需要,而且还有余,一般修饰数量不定的名词(ample time充裕的时间;an ample basket of fruit满满一篮水果;ample space宽敞的空间;ample evidence充分证据)
This leaves her ample time to prepare three meals a day.
这样她就有充裕的时间准备一日三餐饭。
Ample sunshine and rainfall are bringing the crops on nicely
充足的阳光和雨水正使庄稼茁壮地生长。
adequate常用来表示“充足的，完备的，完善的，胜任的”；指数量和质量上复合一个特定的标准或不太高的要求,表示充足的含义上更强调足够用来做某事。
The skater's technique was only adequate.
滑冰者的技术只能说是差强人意。
I hope you will prove adequate to the job.
我希望你证明能胜位这项工作。
Your typing is not adequate for this job.
你的打字不适合这项工作。
His wages are adequate to support these people。
他的收入足以养活这些人。
plentiful 丰富的,很多的,富裕的
.A plentiful harvest is in sight.
丰收在望.(plentiful/good harvest丰收)
Best buy of the week are carrot and cabbage, which are plentiful and cheap
本星期买胡萝卜和洋白菜最合算，因货源充足，价格低廉。
Later, man began to settle in the places where the food and water were plentiful
后来，人们开始在有充足的食物和水的地方定居下来。
sufficient则表示“在数量上是足够的，多的”，在表示充足的含义上更强调多，不缺乏。
Two pounds of orange will be sufficient for the party，don’t buy more.
两磅柑桔就够聚会用的了，不必再多买了。
This is sufficient to show that his argument is false.
这足以证明他的论点是错的。
There's sufficient food to support the people.
有足够的食物供养人民。
