Let's begin at once,it's already late.
问题描述：
Let's begin at once,it's already late.
我们马上开始吧,已经晚了.
Let's begin at once这句的主语是什么啊?
at once是做什么的?
不要it's行吗?
because i don't know.
答
It's already late这里的it功能和it's raining/it's Monday等句型一样,这些都是'无主语句",it除了是代词'它'的含义,还一个功能就是补充担当无主语句的'主语'.只有语法功能,不代表其它的含义.（有点象占位符)Let's be...