美国f签证有哪些？
美国F1签证，是留学生来美国的入境签证类型，包括两种： 常规非移民签证(Non-immigrant Visa) 常规 F-1 Student 学生签 B-2 Visitor Visitor Visas 访客 (B-2 is for tourists， visitng family members and those on business visits. It does not include students attending a course of study unless it's at an institution that’s been designated as a public institutions of study by the U.S. Citizenship & Immigration Services， or USCIS )
特殊非移民签证 ，Special Non-Immi-grant VISA： M-3 Visa Exchange Students exchange student 在以上这两种情况中，M-3 Visa 的身份是可以不用学习的。所以这种visa 不是留学签证而只是一种可以合法留在美国的临时工作签证，一般给那些交换生或者是参加短期培训的学生使用。
F-2， F-3： The spouse and children of F-1 visa holders are entitled to F-2 status， which permits them to attend school in the United States and engage in other lawful activities. In some cases， they also can be employed. If you plan to accompany your F-1 partner/parent， make sure he gets proper approval before his admission so that your application will have less chance of being rejected when submitted with him.
For spouses and unmarried minor children of L-1A and L-1B intracompany transferees who apply within one year from their first entry into the United States under these categories， USCIS may grant permission to accept employment anywhere in the country。 They qualify for this special L-2 worker program if they meet certain criteria related to their employer and length of residence in their home countries， among others. You must petition to change your L-1 status while still maintaining valid nonimmigration visas issued prior to entering the US. If allowed， L-2 workers have the right to work in the U.S. without obtaining another immigration class.
The L-4 visa is intended mainly for employees of foreign embassies， international organizations and major news agencies operating in the USA， but it also applies to those working for multinational companies， independent contractors and executives traveling abroad on company business. An applicant for L-4 status should receive job offer letters showing why he fits the position perfectly and has previous experience and training relevant to it. Furthermore， there might be additional conditions imposed to approve L applications such as a minimum salary