to be ...-ing, to have been ...-ing
Verb て-form +
The auxiliary verb
Continuous Action
Used with verbs that describe a continuous action to show the action is happening right now.
子供が林檎を食べ
The child is eating an apple.
雨が降っ
It is raining.
Resultant State
Used with verbs that describe a change or a specific event to show the resulting state still remains.
窓が開い
The window is open.
その話を知っ
I know that story.
When used with action verbs like 食べる or 走る, it indicates an ongoing action (is doing). When used with change-of-state verbs like 行く, 来る, or 結婚する, it indicates a state that remains after the action has finished (has done). In casual speech, the い in