Look is not part of the action here. Look is just used in that example to get someone’s attention. In this case in real life, you would point to the window and say “Look! Someone has broken the window.” The window is already broken. That happened at some point in the past and is over now. It’s not in the process of still being broken.

"Look, somebody has been breaking the window"sounds kind of ridiculous to me as breaking the window is not an action that lasts for a big period of time. It happens in one moment. So when you say "look, somebody has broken the window" you're focusing on the fact that the window has been broken and try to catch people's attention to it. You can say it when you hear a sound of broken glass, come to where you thought that sound came from and and see a broken window and somebody running away.

Hi Sue. In #2 the "breaking" is the continuous action. #2 is grammatically correct, but it's wrong because it doesn't make sense. Things break in an instant in time, so it is strange to say "this window is being broken". On the other hand, it takes time to eat a cake, so if you find a half-eaten cake, you CAN say "someone has been eating this cake!" (they have started eating the cake but have not finished). Wow this is a little hard to explain! :) Does this make sense? John

As (scarily few) people have said 'breaking' doesn't make sense with _one_ window. But you could use it with windowS. e.g. If there is a row of old windows, and most are broken, you could say "somebody has been breaking those windows", suggesting they have been broken over time. Also 'look' is not continuous. It is imperative.

Both are right but mean different things. In "someone has been breaking" the emphasis is on someone doing something like breaking the window for a while. Probably, the emphasis is on "someone" here. In "someone has broken", the emphasis is on the fact that the window is broken. ****