f1签证到期怎么续签？
F-1身份，在美国留学的学生，如果I20表上面的valid from 和to 日期都在有效期内的话，那么学生就可以合法留在美国并且合法学习，这段时间也被称为合法status. 如果在合法的status下超过了一年没有离境，那么就叫做overstay. 在美国的留学生被允许的合法停留时间根据学生的不同的状态是不同的：
1) F-1， M-1， and J-1 visa holders in status are allowed to stay for an unlimited time while studying， provided that they remain current on their educational and/or employment documents (i20's etc)， but must leave the US if they cease school or work enrollment;
2) Students who have been granted OPT， STEM OPT， CPT， or Curricular Practical Training may extend their authorized period of stay during which they can legally work up to six months each before they must leave the United States；
3) F-1 students with a Sevis record at a Designated School Official may apply for an extension of stay called "dual intent"； Dual intent is the ability to seek a change of status when already present in the U.S.， such as by applying for immigrant visas. With dual intent， F-1 students are able to seek lawful permanent residence without leaving the country first. Dual Intention only applies to those who filed I485， Application for Change of Nonimmigrant Status on the basis of having obtained a degree from a U.S. institution within five years after admission into the United States. It does not apply to international student who has completed less than two full academic years of study or any nonimmigrant seeking adjustment of status under INA Section 245(a)， nor does it apply to foreign nationals entering the U.S. on another immigration status（not including F，M，J）. The Department of Homeland Security will still consider applicants eligible for dual intent if they meet these criteria． As such， it would be best to consult an experienced lawyer. For more information visit USCIS website： URL However， according to a recent court ruling（Hernandez v. DHS， Case No. CV 17-953-GPC-WVG， April 6， 2018)， dual intent no longer exists unless an applicant falls under specific conditions outlined above. Therefor， you should always check your individual case before consulting an attorney regarding filing for D