我知道去 Canada 或 Mexico 30 天内回 US 不需重新签 US visa, 用旧 I-94 即可. 父母 visa 属 multiple-entry, 最初入境时获 six months stay. 如果出境时 (to Canada or Mexico) 主动递交 I-94, 再入境时(US visa still valid) 能否获新 I-94 并且 another six moths stay ? 飞机/汽车哪个保险些 ? Thanks a lot for advice !
p.s.: With the use of multiple-entry visa, we are trying to avoid the side affect of extension (making the visa applications harder in China later on). Not sure if re-entry can actually 'reset' their entry records, though :-)