sea是可数名词吗

　　例句：

　　The waste was dumped in the sea .

　　废物倒入海中。

　　The wreck is lying at the bottom of the sea.

　　沉船躺在海底。

　　He looked down at the sea of smiling faces before him.

　　他看着眼前这笑脸的海洋。

　　The sea covers nearly three-fourths of the world's surface.

　　海洋几乎占地球表面的'四分之三。

　　The small craft was exposed to the danger of the open sea.

　　那只小船曾经历了在空旷的海洋里穿行的种种危险。