选词填空
schoolcars easyairexercise
Many people in the world ride bikes every day.There are more bikes than_____in the world today.A lot of Chinese people ride bikes to go to work or_____.Bikes are much cheaper than cars.And it is_____forpeople to learn to ride.Bikes are also used for_____.It helps us to keep fit. If each family has a car,it will use a lot of energy and pollute the_____.So let us ride bikes.