Birds are good pets, they can wake you up by singing in the morning.
鸟是很好的宠物,它们早上的歌声可以将你从梦中唤醒。
Our knowledge of the oceans a hundred years ago was confined to the two-dimensional shape of the sea surface and the hazards of navigation presented by the irregularities in depth of the shallow water close to the land.
100年前,我们只知道海洋是二维平面形的,以及靠近陆地浅水区的深浅不一能给航行带来危险。