3 sentences

1. 他是嫡长子，故而被立为冢子。

   tā shì dí​chǎng​zǐ, gù'ér bèi lì wéi zhǒng zǐ.

   As the eldest son of the primary wife, he was established as the heir.

   Source: Dong Chinese Dictionary

2. 这座荒野中的古冢已经存在了几百年。

   zhè zuò huāng​yě zhōng de gǔ zhǒng yǐ​jīng cún​zài le jǐ​bǎi nián.

   This ancient mound in the wilderness has existed for hundreds of years.

   Source: Dong Chinese Dictionary

3. 考古学家在这座巨大的古冢里发现了许多陶器。

   kǎo​gǔ​xué​jiā zài zhè zuò jù​dà de gǔ zhǒng lǐ fā​xiàn le xǔ​duō táo​qì.

   Archaeologists discovered many pieces of pottery in this massive ancient burial mound.

   Source: Dong Chinese Dictionary