a large quantity of 后面可接可数名词或不可数名词,接不可数名词时谓语动词用单数,接可数名词复数时谓语动词用复数（少数人认为也要用单数）
large quatities of 后面接可数或不可数名词时谓语动词多要用复数（因为quantities本身用了复数）
A large quantity of milk was reported not to reach the standard
A largr quantity of students don't like English.
Large quantities of water are wasted every year.
amount 一般后面接不可数名词,所以a large amount of 后面谓语动词用单数,而large amounts of 后面接不可数名词时谓语动词也要用复数
A large amount of money has been wasted
Large amounts of money have been wasted.