3 sentences

1. 经过整顿，这里的环境大为改观。

   jīng​guò zhěng​dùn, zhè​lǐ de huán​jìng dà​wéi gǎi​guān.

   After the cleanup, the environment here has greatly improved.

   Source: Dong Chinese Dictionary

2. 经过几年的治理，这个贫困村的面貌发生了巨大改观。

   jīng​guò jǐ nián de zhì​lǐ, zhè​ge pín​kùn cūn de miàn​mào fā​shēng le jù​dà gǎi​guān.

   After years of management, the outlook of this poor village has changed dramatically.

   Source: Dong Chinese Dictionary

3. 听了他的解释，我对他之前的印象有所改观。

   tīng le tā de jiě​shì, wǒ duì tā zhī​qián de yìn​xiàng yǒu​suǒ gǎi​guān.

   My impression of him has improved after hearing his explanation.

   Source: Dong Chinese Dictionary