4 sentences

1. 法院裁定该协议无效。

   fǎ​yuàn cái​dìng gāi xié​yì wú​xiào.

   The court ruled that the agreement was invalid.

   Source: Dong Chinese Dictionary

2. 我丈夫死了，所以赌约无效。

   wǒ zhàng​fu sǐ le, suǒ​yǐ dǔ​yuē wú​xiào.

   My husband is dead, so the bet is invalid.

   Source: OpenSubtitles

3. 由于缺少必要的签名，这份合同被视为无效。

   yóu​yú quē​shǎo bì​yào de qiān​míng, zhè fèn hé​tong bèi shì​wéi wú​xiào.

   Due to the lack of necessary signatures, this contract is considered invalid.

   Source: Dong Chinese Dictionary

4. 这种治疗方法对他的病情完全无效。

   zhè zhǒng zhì​liáo fāng​fǎ duì tā de bìng​qíng wán​quán wú​xiào.

   This treatment method is completely ineffective for his condition.

   Source: Dong Chinese Dictionary