3 sentences

1. 他是这所大学的校友。

   tā shì zhè suǒ dà​xué de xiào​yǒu.

   He is an alumnus of this university.

   Source: Dong Chinese Dictionary

2. 他在大学期间加入了一个校友联谊会。

   tā zài dà​xué qī​jiān jiā​rù le yī gè xiào​yǒu lián​yì​huì.

   He joined an alumni association during university.

   Source: Dong Chinese Dictionary

3. 在校庆典礼上，他被授以荣誉校友的称号。

   zài xiào​qìng diǎn​lǐ shàng, tā bèi shòu yǐ róng​yù xiào​yǒu de chēng​hào.

   He was awarded the title of Honorary Alumnus at the school anniversary ceremony.

   Source: Dong Chinese Dictionary