1. He got a nasty knock on the head.

2. You've had a nasty knock on the head.

3. He got a knock on the head when he fell.

4. She got a nasty knock on the head when she fell.

5. He received a nasty knock on the head from a falling slate.

6. But it does rather knock on the head the idea that the conflict in the Middle East persists solely because of Israeli obduracy and America's failure to lean on Israel hard enough.