2 sentences

1. 他们联名签署了一封抗议信。

   tā​men lián​míng qiān​shǔ le yī fēng kàng​yì xìn.

   They jointly signed a letter of protest.

   Source: Dong Chinese Dictionary

2. 许多学者联名上书，建议政府加强文物保护。

   xǔ​duō xué​zhě lián​míng shàng​shū, jiàn​yì zhèng​fǔ jiā​qiáng wén​wù bǎo​hù.

   Many scholars jointly petitioned the government to strengthen the protection of cultural relics.

   Source: Dong Chinese Dictionary