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

Even though they are not doubtful at all _______ John will pass the exam, I still wonder ______ he is fully prepared

Most doctors and nurses ______ whiteclothes when they’re at work..

This is the museum _____ we visited last year.

“Nothing in this letter＿＿＿be considered as a license to use the artist’s personal possessions”, the judge declared on the court.