的笑話
500miles' son: Dad, if an airplane leaves Chicago and flies 500 miles an hour west with a 300 mile an hour wind coming East for two hours, and then flies 600 miles an hour with a 100 mile an hour wind coming East, and then flies 700 miles an hour for 2 hours with no headwind, how far will that plane have flown?
500miles: Son, I'll call my office in the morning and have you switch to an easier flight.
