a large amount of作主语的主谓一致

amount用作名词时，意为“数量”“金额”等，通常用于 a (great, large) amount of 这类结构，其后通常接不可数名词。如：

There was a fair amount of traffic on the roads. 路上的车辆颇多。

An increasing amount of organic produce is to be found on supermarket shelves. 越来越多的有机产品出现在超市货架上。

这类结构用作主语，其谓语的数取决于 amount 的数。如：

在这座桥上花了大量资金。

正：A large amount of money was spent on the bridge.

正：Large amounts of money were spent on the bridge.

注：偶尔也可见到其后接复数可数名词的用法，但不算普通。如：

The shopkeeper had a large amount of oranges in his storeroom. 店主在货仓里存有大量橙子。——摘自《朗文当代高级英语词典》

Even small amounts of these substances are known to cause skin problems. 我们知道这种物质即使是一丁点也会损害皮肤。——摘自《剑桥高阶英词典》