You arrive to the airport but your flight is cancelled. What comes to your mind?
It must have been cancelled because of a storm
You can't find your keys. Later you find them inside your fridge!
I must have left it there when I had breakfast.
Your friend, who never gets bellow 90% on his grades, just flunked geography.
He must have had problems at home.
You hear a loud noise coming from the living room. When you check it, your TV is on the floor, broken.
It must have been my cat!
Your friend had a very important project to complete. When you see him/her today, you see that he/she is very happy, but very tired.
He/she must have stayed all night working.
You try to open your front door but it's locked. You remember you were the last one to leave the house this morning.
You must have locked it when you left.
You left a slice of chocolate cake on the counter 10 minutes ago. You went to the bathroom and when you came back it was not there anymore!
It must have been my sibling!
Your teacher comes to the first class after the tests and he is smiling... A LOT!
You must have done well!
Jenny is alone at home. She hears a loud BANG! What happened?
It must have been her cat!