sub-,在下，marine,海的。

1. He detected a ship moving down the starboard side of the submarine.

他发现有一艘船正在潜艇的右侧航行。

2. We were trying to plot the course of the submarine.

我们试图标绘出潜艇的航线图。

3. In contrast with its surface fleet, Britain's submarine force was relatively small.

同其水面舰队相比，英国的潜艇部队规模相对较小。

4. The captain of the submarine has got this periscope thing.

那个潜艇艇长有个类似于潜望镜之类的东西.

5. The submarine had had time to submerge before the warship could approach.

潜水艇没等军舰靠近就及时潜入水下了。