The entry point tissue in the very front of eye functions as the window ______ all light has to pass on its way.
If you have any difficulty ____ how to skate, you can turn to Jacky.
He is such a good teacher ______ we all respect.
They are talking _______ they were old friends.
____ it is to skate on real ice!
From the ______ expression on his face we can guess something ______ must have happened to him.