Bill was a very good pilot. He had been in the air force for several years, and had been very successful. Now he was sent to a small field in the middle of a forest,    1    planes were able to attack the enemy very easily,    2    it was near the front line, but    3    to find. The forest trees were very tall and very    4    on all sides, so planes had to go down very quickly and then stop their falling very    5    before they    6    .