回複：是否需要撤銷H4的申請？

加拿大公民。H-1B， I-140批準。被layoff。立即申請轉H4。收到Receipt。後找到工作。成功轉成TN。但是H4申請仍在Pending中。根據Last approvement governs的原則，是否以後H4批準了，TN就自動被覆蓋，成了H4？如果答案是肯定的。是否必須趕快撤銷H4的申請？
-Did you get the TN I-94 at the US-Canada border? If yes, the H-4 application is invalid automatically. But sometimes the IO may forget this rule and approve your H-4, so you had better write a letter to request withdrawal of the H-4 application (provide the copy of the H-4 receipt).