回复：是否需要撤销H4的申请？

加拿大公民。H-1B， I-140批准。被layoff。立即申请转H4。收到Receipt。后找到工作。成功转成TN。但是H4申请仍在Pending中。根据Last approvement governs的原则，是否以后H4批准了，TN就自动被覆盖，成了H4？如果答案是肯定的。是否必须赶快撤销H4的申请？
-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).