You should take the train instead of the bus

1. You should take the train instead of the bus.

-> If................................................ .................................................. ..................

2. I'm sure that someone forgot to lock the door.

--> Someone must.............................................. .................................................

3. They bought this house ten years ago.

--> They have.............................................. .................................................. .....

4. The course finished with a big party.

--> At the end............................................... .................................................. ....

5. We invited a pop star onto the chat show, but he didn't turn up.

--> The pop star.............................................. .................................................. ..