3 sentences

1. 他花了两天时间撰写这份计划书。

   tā huā le liǎng tiān shí​jiān zhuàn​xiě zhè fèn jì​huà​shū.

   He spent two days writing this proposal.

   Source: Dong Chinese Dictionary

2. 他在退休后开始撰写自己的回忆录。

   tā zài tuì​xiū hòu kāi​shǐ zhuàn​xiě zì​jǐ de huí​yì​lù.

   He started writing his memoirs after retiring.

   Source: Dong Chinese Dictionary

3. 他正在撰写一篇关于人工智能的论文。

   tā zhèng​zài zhuàn​xiě yī piān guān​yú rén​gōng zhì​néng de lùn​wén.

   He is writing a thesis on artificial intelligence.

   Source: Dong Chinese Dictionary