8He was so deep in thought, thinking of the problem ______ he knocked into the tree without noticing it

I couldn’t remember the exact date of the storm, but I knew it was ________ Sunday because we were on ________ field trip.

Could you please ____me some suggestions for the plan?

Tom, you are going to buy a new flat here,aren’t you?— Yes, but I can’t _____anexpensive one.

This book______Tom’s,because his name is on the book.