3 sentences

1. 他在海外经商多年。

   tā zài hǎi​wài jīng​shāng duō nián.

   He has been doing business overseas for many years.

   Source: Dong Chinese Dictionary

2. 他放弃了铁饭碗，决定下海经商。

   tā fàng​qì le tiě fàn​wǎn, jué​dìng xià​hǎi jīng​shāng.

   He gave up his secure government job and decided to go into business.

   Source: Dong Chinese Dictionary

3. 他通过多年的经商积累了巨大的财富。

   tā tōng​guò duō nián de jīng​shāng jī​lěi le jù​dà de cái​fù.

   He accumulated great wealth through years of business.

   Source: Dong Chinese Dictionary