Stare at

　　Spend…time （in） doing

　　Run across/into sb./sth.

　　Make a contribution to

　　Go over

　　1. Any word longer than a couple of syllables gave me trouble.

　　2. I have never been able to thank him properly because I never knew then what an enormous contribution he was making to my life.

　　3. That became a habit， as did all the other things he left me with.