1.   Desperately, Irvin racked his brains, but there was nothing he could tell them.

2.   He racked his brains, he cast his mind back.

3.   If we all rack our brains we should come up with some ideas.

4.   She racked her brains, trying to remember what David had said.

5.   They sat in silence, racking their brains for the name of the road.

6.   I racked my brains, trying to remember his name.

7.   She began to rack her brains to remember what had happened at the nursing home.

8.   I racked my brains.

9.   I delayed switching the computer off while I racked my brain trying to think of some way of saving them, but there was none.

10.   He paused to rack his brains.