This cosmic cannonball is challenging theories to explain its blistering speed.这个宇宙加农炮正在挑战解释其起泡速度的理论.Suddenly , a sporadic cannonball bombed in the battle field.敌人已经在城下骂阵了,我们却还是按兵不动.It must be a cannonball.那一定是一发炮弹....
苏格兰的地形the physical geography of Scotland他对地形作了缜密的研究.He had made a detailed study of the terrain.我们不熟悉新英格兰的地形.We're unfamiliar to the geography of New England....