单项选择题
A．they could travel by wagons B．they could ride on their tame animals and go across water in hollowed tree trunks C．the roads were splendid D．the climates were favorable
A．for joy B．from necessity C．to broaden the mind D．to escape from the wild animals
A．so we can travel anywhere without difficulty B．because we are provided with all kinds of convenient means for traveling C．because traveling organizations can be found in the countries the world over D．so travelers have increased rapidly