During the winter months, ten feet of snow was not an unusual occurrence.

Not an unusual occurrence except that a military medical official was brought along as part of the group.

It seems to me to be a very unusual occurrence.

It is not a terribly unusual occurrence on the hill.

He had the feeling that her tears were an unusual occurrence anyway.

An unusual occurrence, he was not subject to such weakness.

It is not my fault that so unusual an occurrence has taken place tonight.

This successful ending was an unusual occurrence during the war.

But you would do well to report any unusual occurrence.

It hasn't been an unusual occurrence, much less shocking, for coming on thirty years now.