专业为外国企业及个人代办在中国签证延期，外国人签证种类变更（L转F，F对F延期有效期3个月/6个月/1年多次出入境中国）Tourist L change to business F(single/double/6-months or 1-Year multiple entries )No.2 解决过期40天内的签证问题（只可以变更成为半年多次往返中国的商务签证F种类）Fix the problems if visa expired within 40days,can make it become F types