感谢8老师和jordy3388的热心解答！还请指点：如果我们3月初去加拿大一趟回来，大概6月中旬回国（不过也许是9月初才回国），估计我妈妈2014年初就可以再次申请B2签证入境吧？如果现在办延期半年，也是准备6月中旬回国，是不是就要等2014年夏天后才能再次申请B2签证入境呢？
-Normally your mother had better stay in China for one year (no matter whether she stay in US for 6 months or one year) and then, apply for the B2 visa again. If she applys for the visa too soon, more possibility the visa applicaiton may be denied.
我妈妈的B2签证是3月5日到期，现在网上递交申请延期来得及吗？
-Yes. As long as she files the extension applicaiton before the I-94 expires, it will be fine.
万分感谢！
