a lot of可以等同于lots of或者many，意思是很多。修饰可数名词复数或不可数名词。例句：There are a lot of books in the library.

意思相同的词(组)还有：

many修饰可数名词

much修饰不可数名词

a great number of修饰可数名词

a great amount of修饰不可数名词

a great deal of修饰不可数名词

plenty of修饰可数名词