第一次换学校，也是从H1b=>H1b, 没有给H4办什么材料。
这次也是H1b=>H1b，学校到学校，这第三个学校要求填
Form I539.
http://uscis.gov/graphics/formsfee/forms/i-539.htm
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Purpose of Form: This form is used by some nonimmigrants to request extensions of stay or changes from one nonimmigrant category to another nonimmigrant category. Please see the form's instructions for your specific nonimmigrant visa category.
It is used by F and M nonimmigrants seeking reinstatement of status.
It is also used by K-3/4 nonimmigrants to request extensions of stay and by persons seeking V nonimmigrant status while in the United States or extension of stay as a V nonimmigrant.
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上面虽然没有提到H4,但是在表格的填写指南中有专门的H4一栏．
有谁填过这个539表，能不能分享一下经验？
有知道的也请回答，先谢过了。