1 If Kevin hadn't just got a text message, he wouldn't have looked at his mobile phone.
2 If he hadn't looked at his mobile, he would've seen the banana skin.
3 If someone had picked up the banana skin earlier, it wouldn't have been there.
4 If Kevin had seen the banana skin, he wouldn't have stood on it.
5 If he hadn't stood on it, he wouldn't have fallen over.
6 If he hadn't fallen over, he wouldn't have broken his mobile.
7 If he hadn't broken his mobile, he would have replied to the text message.