1) Cows have best friends and can become stressed if they are separated.

2) The first car with air conditioning was released in 1939.

3) The first commercial mobile phone, the Motorola DynaTAC 8000X, was released in 1983 and weighed nearly 2 pounds.

4) The first successful portable MP3 player, the Diamond Rio PMP300, was released in 1998 and could hold up to 60 minutes of music.