一熟人的未婚孩子移民（Follow-To-Join）实际时间表：
09/13/2021: 移民签证批准 09/22/2021: Paid immigration fee 12/12/2021: 西雅图入境 01/01/2022: 收到SSN卡 01/29/2022: OS155A 批准 （green card was ordered to be produced)
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