It's a waste of time,这个a是表示什么?

It's a waste of time,这个a是表示什么? It's a waste of time这个句型,急, It's a waste of time exactly! 请问:It's a waste of time.是浪费时间,那么a waste of waters为什么又译成茫茫大海 I --- --- shopping.It's a waste of time. it's a waste of time your talking to him It's a waste of time doing sth. it is a waste of time to do 这个句子 it was a waste of time and It is only a waste of time a waste of time It's a waste of time to spend so much time on gardening.