3 sentences

1. 他走在女孩几公尺之前，以防万一。

   tā zǒu zài nǚ​hái jǐ gōng​chǐ zhī​qián, yǐ​fáng​wàn​yī.

   He walked a few meters ahead of the girl, just in case.

   Source: CCMatrix

2. 即使如此，我总是确保我准时，以防万一医生也是如此。

   jí​shǐ rú​cǐ, wǒ zǒng​shì què​bǎo wǒ zhǔn​shí, yǐ​fáng​wàn​yī yī​shēng yě​shì rú​cǐ.

   Even so, I always make sure I am on time, just in case the doctor is too.

   Source: CCMatrix

3. “哦，以防万一，这是我的姓名和地址，“他说，递给她一张卡片。

   “ ò, yǐ​fáng​wàn​yī, zhè shì wǒ​de xìng​míng hé dì​zhǐ,“ tā shuō, dì gěi tā yī zhāng kǎ​piàn.

   “Oh, just in case, here’s my name and address,” he said, handing her a card.

   Source: CCMatrix