因為在國內有至今還未處理好的棘手事情，所以一直沒有登陸美國，請問老師，
-Check the immigration visa to see whether it expires or not (normally it is valid for 6 months). If not, you can enter US using that visa. If it expired, you can not use it any more.
If you enter US with this valid immigration visa, you will get the lawful permanent residency/status (green card)immediately at the port of entry. The CBP officer will endore your immigration visa (put green card stamp) on your passport and you can use this stamp for the international travel and work. of course, USCIS will send you the physcial green card to you in about one month.
我可否現在進入美國，提交綠卡申請，小住2個禮拜，然後回中國，等待綠卡批準，請朋友把綠卡寄給我？等我處理好國內的事情再用綠卡回美國？
-Not need 提交any綠卡申請 (see above answer). You also do not need 朋友把綠卡寄給you because you can use the green card stamp to come back.
