2 sentences

1. 这艘驱逐舰正在海上执行任务。

   zhè sōu qū​zhú​jiàn zhèng​zài hǎi shàng zhí​xíng rèn​wu.

   The destroyer is on a mission at sea.

   Source: Dong Chinese Dictionary

2. 两艘驱逐舰正在为运输船队护航。

   liǎng sōu qū​zhú​jiàn zhèng​zài wèi yùn​shū chuán​duì hù​háng.

   Two destroyers are escorting the transport fleet.

   Source: Dong Chinese Dictionary