The Great wall winds its way from the west to the east _____ the mountains,

问题描述:

The Great wall winds its way from the west to the east _____ the mountains,
across the deserts and _____ the valleys.
A.across; through B.over; across C.over; through D.through; over 为什么?为什么?

这么记 mountains 山脉 跨越山脉 山脉高耸 在山脉上 over
而 valleys是山谷 山谷有沟壑 所以要穿过山谷 意会一下 就是在山谷中 所以用through