Terravision bus is probably the easiest and cheapest connection between Fiumicino airport and Rome city centre, but the journey takes 55 minutes. However, you should consider that they oversell buses online and you may to wait more than two hours to catch one. The online "reservation" does not guarantee a seat. You can either book online (€4 one-way) or buy the tickets there (€6 one-way, €11 round-trip). The bus departs near Terminal 3 of the airport and arrives at Termini station (the same applies for the route in reverse). There are other buses that go to Termini station and, during the low season, you can hedge your bets and see which one leaves earlier. Be careful terravision is not always on time and you might get late to your flight.
Consumer Reports points out that you can test your smoke alarm’s sensors using a test spray that simulates smoke, but that the best thing is to just replace an alarm that has passed its expiration date. Check for the date by looking for the manufacture date on the underside of your alarm (the part that typically faces the ceiling). Add ten years to that date and you have your expiration date. You might want to write this date on a piece of painter’s tape or on the outside of the alarm so it’s easy for you to see when to pick up a new one.