3 sentences

1. 防盗警报器突然响了起来。

   fáng​dào jǐng​bào​qì tū​rán xiǎng le qi​lai.

   The burglar alarm suddenly sounded.

   Source: Dong Chinese Dictionary

2. 他给家里换了一把防盗锁。

   tā gěi jiā lǐ huàn le yī bǎ fáng​dào suǒ.

   He replaced the lock at home with an anti-theft one.

   Source: Dong Chinese Dictionary

3. 离开房间时请关好门窗，注意防盗。

   lí​kāi fáng​jiān shí qǐng guān​hǎo mén​chuāng, zhù​yì fáng​dào.

   Please close the windows and doors when leaving the room and watch out for theft.

   Source: Dong Chinese Dictionary