有一读者问： 有这样一道选择题：
(1)There_________a large quantity of books in the library.
A. is B. are C. have D. has
答案是A，并说a large quantity of后面不论接单数名词或复数名词，其谓语动词一律用单数；谓语动词的变化与quantity有关，与其后的名词无关。而我们的语法书上却说“a quantity of+名词”后的谓语动词应与a quantity of后的名词的数一致。我们很不理解，请答。
此答案是正确的，是符合语言实际的。之所以如此，可能是由于a quantity of与a number of不同，前者强调“量”，后者强调“数”，再如：
(2)A quantity of books is found on the table.
(3)A large quantity of weapons and ammunition was seized from rebel hide-outs in the operation.
但“quantities of+单数名词或复数名词”之后则用复数动词，如：
(4)Quantities of sand were washed down the hillside by the rain.
(5)Quantities of surplus materials are available.
你的语法书上所说的规则原则上也不错。但与语言实际不甚符合。它似乎更适用于a lot of, a number of等短语。
