3 sentences

1. 董先生是这家公司的创始人。

   Dǒng xiān​sheng shì zhè jiā gōng​sī de chuàng​shǐ​rén.

   Mr. Dong is the founder of this company.

   Source: Dong Chinese Dictionary

2. 他作为这所中学的校董，捐赠了许多书籍。

   tā zuò​wéi zhè suǒ zhōng​xué de xiào dǒng, juān​zèng le xǔ​duō shū​jí.

   As a trustee of this middle school, he donated many books.

   Source: Dong Chinese Dictionary

3. 由于主管休假，这些账目暂由他负责董理。

   yóu​yú zhǔ​guǎn xiū​jià, zhè​xiē zhàng​mù zàn yóu tā fù​zé dǒng lǐ.

   Since the supervisor is on leave, he is temporarily in charge of managing these accounts.

   Source: Dong Chinese Dictionary