3 sentences

1. “北大”是北京大学的简称。

   “ Běi Dà” shì Běi​jīng dà​xué de jiǎn​chēng.

   'Beida' is the short name for Peking University.

   Source: Dong Chinese Dictionary

2. “北京大学”常被缩称为“北大”。

   “ Běi​jīng dà​xué” cháng bèi suō chēng​wéi“ Běi Dà”.

   'Peking University' is often abbreviated as 'Beida'.

   Source: Dong Chinese Dictionary

3. 他是北大毕业的。

   tā shì Běi Dà bì​yè de.

   He graduated from Peking University.

   Source: Dong Chinese Dictionary