4 sentences

1. 这项研究前后历时十年才最终完成。

   zhè xiàng yán​jiū qián​hòu lì​shí shí nián cái zuì​zhōng wán​chéng.

   This research took a total of ten years to complete.

   Source: Dong Chinese Dictionary

2. 文章的前后内容互相呼应，结构非常严谨。

   wén​zhāng de qián​hòu nèi​róng hù​xiāng hū​yìng, jié​gòu fēi​cháng yán​jǐn.

   The different parts of the article echo each other, creating a very rigorous structure.

   Source: Dong Chinese Dictionary

3. 他打算在国庆节前后去北京旅游。

   tā dǎ​suàn zài Guó​qìng​jié qián​hòu qù Běi​jīng lǚ​yóu.

   He plans to travel to Beijing around the National Day holiday.

   Source: Dong Chinese Dictionary

4. 房子前后都种满了红色的玫瑰花。

   fáng​zi qián​hòu dōu zhòng mǎn le hóng​sè de méi​guī​huā.

   Red roses are planted all around the front and back of the house.

   Source: Dong Chinese Dictionary