cheapest. five
Planes are much faster t______ underground,trains,taxes and buses.Buses are the c____and the slowest of the f_____.Taxes run more quickly than buses,but they are more e_____.Underground trains are not as f_____ as planes,but they run as quickly as trains o_____ the ground.Underground trains are the second cheapest of them and the most c______.
答案：
than.cheapest.five.expensive.fast.on.comfortable