In the past men had great difficulty in ploughing their lands to grow food. But to day giant machines are used to plough thousands of acres of land.As a result,more food can be grown in a shorter time than was possible before.Food grown in one country is snt to another country where it is needed badly.To carry the food motor-vehicles, steam-ships and various other means of transpot have been invented.Shortage of food in one place no longer causes anxiety as it can be brought from another place within a very short time.