He could have done that because he does it often, however, he can’t have done anything else because he was not there when the unlucky incident happened.
Mógł to zrobić, bo często to robi, jednak nie mógł zrobić nic innego, bo nie było go tam, kiedy zdarzył się ten niefortunny incydent.
Before going out I will have checked my mail and I will have found out who has written to me in order not to regret going out before having checked my mail first.