Your mental power?! Click here to see it. (in English, please!)

1. A chemist discovered that a certain chemical reaction took 80 minutes when he wore a tweed jacket. When he was not wearing the jacket the same reaction always took an hour & 20 minutes. Can you explain?
2. A customer in a restaurant found a dead fly in his coffee. He sent the waiter back for a fresh cup. After a sip he shouted, "this is the same cup of coffee that I had before!" How did he know?
3. I guarantee, said the pet-shop salesman, "that this parot will repeat every word it hears". A customer bought the parot but found it would not speak a single word. Nevertheless, the salesman told the truth. Can you explain?