题目内容：

单选 They had___fun at the party
They had___fun at the party
A a lot
B lots of

优质解答

a lot of=lots of ,后接名词,既可以修饰可数也可修饰不可数.接名词时要有of.
a lot可作副词,如 He ate a lot.他吃了很多.
此句fun 为不可数名词,故用有of的形式,选B.