Rick (have/has) a grandfather.His grandfather (is/are/am) not very old.He (Iike/Iikes) to swim and to play ping-pong.He (swim/swims) very well.He can (ride/rides) a bike, but not very well.Rick (help/helps his grandad on the farm.Rick (feed/feeds) the horses and the cows.In the evening Rick and his grandad (read /reads) books and ( play /plays ) computer games. Почему где нужно s a где нет,что за правило применяется ​