✔ 最佳答案
(1) This is a codeshare (聯營) flight between AA & CX, operated by CX, i.e. 係國泰機
(2) Although you check through luggages to Phoenix, you MUST claim your luggage in Chicago, as Chicago is the first port of entry in the U.S. After going through customs (清關) in the arrival terminal (usually Terminal 5), you'll need to take your luggages to the connecting flight terminal (probably Terminal 1) to re-checkin the luggages.
For security purposes, all check-in luggages MUST NOT BE LOCKED.
From Terminal 5 to Terminal 1, you can either take shuttle bus, or train.
參考: myself -- I've transitted in Chicago many times, it's really a busy airport.