2 sentences

1. 他在合同上盖了公章。

   tā zài hé​tong shàng gài le gōng​zhāng.

   He stamped the contract with the official seal.

   Source: Dong Chinese Dictionary

2. 请在合同末页加盖公章。

   qǐng zài hé​tong mò yè jiā​gài gōng​zhāng.

   Please stamp the official seal on the last page of the contract.

   Source: Dong Chinese Dictionary