Here are the answers with explanations:
- Always look through the peephole / chain before you open the door. (It's safer to look through the peephole to see who is outside.)
- Don't run after / hand over the burglar! (You should not chase after a burglar; it's dangerous. Instead, call the police.)
- A burglar let / broke into our house yesterday. ('Broke into' means to enter illegally, often by force.)
- He is installing / stealing an alarm system. ('Installing' means setting up a new system.)
- Keep your mobile phone switched / fitted on at night. (Switched on means turned on.)