收到的EAD卡，但是有個問題COMBO

剛剛收到EAD卡，上麵最後一行寫著serves as I-512 advance parole，是不是意味著這個也就是我的返鄉卡，我可以買機票回家了？

另外，隨著卡寄來的紙上寫著這個卡式combo card，說the combo card permits you to work in the united states and to travel outside the united states and return while your form I-485 is pending with USCIS.

但是那張紙的最後一行仍舊用紅字寫著“if you have received a combo card, please see important information on reverse before traveling outside the united states. Parole upon your return to the untied states is not guaranteed.”

combo card到底能不能充當返鄉證啊？聽起來，即使拿著這個combo card 回美國時的入境好像還是沒有保證阿？這個combo card到底能不能充當返鄉證啊？