3 sentences

1. 他是这家报社的特约记者。

   tā shì zhè jiā bào​shè de tè​yuē jì​zhě.

   He is a contributing correspondent for this newspaper.

   Source: Dong Chinese Dictionary

2. 他是这家报社派驻海外的特约通讯员。

   tā shì zhè jiā bào​shè pài​zhù hǎi​wài de tè​yuē tōng​xùn​yuán.

   He is a special correspondent for this newspaper stationed overseas.

   Source: Dong Chinese Dictionary

3. 他的文章是该刊物的特约稿件。

   tā de wén​zhāng shì gāi kān​wù de tè​yuē gǎo​jiàn.

   His article is a specially commissioned piece for this publication.

   Source: Dong Chinese Dictionary