Кто знает англ, совсем не сложно)

1. He fired his gun (a-on,b-by,c-at) the bird.
2. water was running (a-over,b-across,c-thought) the hill.
3. They haven't been at the seaside (a-since,b-for,c-about) 3 years.
4.This book was written (a-with,b-at,c-by) a gifted writer.