an amount of 与 amounts of 的区别?(不清楚的求别误导,)

an amount of 与 amounts of的区别
只不过都是amount,amount是修饰不可数名词：
an amount of +不可数名词,谓语动词用单数；
amounts of+ 不可数n 谓语动词用复数同样修饰不可数名词
前者谓语动词用单数
后者谓语动词用复数A large amount of damage has(谓语动词单数) beend one by the earth quake． Large amounts of money were(谓语动词复数) spent on the bridge．A large amount of damage has been done by the earth quake． Large amounts of money were spent on the bridge．谢谢真专业