Question

i ______(wait)an hour when u came to see me

Answer 1

I had been waiting for an hour when you came to see me.

Here, I've been waiting here for hours implies that the action has been occurring and is still occurring at the time when you are saying it ("I've been waiting here for hours and he still hasn't shown up!").

"I waited here for hours" is better used to describe an action which was completed in the past ("I waited here for hours yesterday and the man never showed up.")

Answer 2

Hi,

Here is your answer,

Question = I ______(wait)an hour when u came to see me

Answer =  I had been waiting for an hour when you came to see me.

Hope it helps you !