我持F1签证；我妈妈是B2签证,明年2月份到期。因为需要我妈妈帮我带小孩，所以想给我妈申请B2延期。请问：
1.在我是F1的情况下可以给我妈妈申请B2延期吗？
-It is irrelevant to you.
2.申请材料需要准备银行存款证明，请问是需要我的存款证明还是我妈妈的？
-Your mother's. You are a student and are not suppose to have money (income).
3.中国的银行证明是否可以，还是必须是美国的？
-It does not matter as long as she can get the money from the bank to support her cost during travel in US.
4.银行证明的存款额度大概多少比较合适？
-Enough for the cost in US.
5.是否需要提前预定好未延期的回程机票并附在申请材料中，以表示如果不通过也会按时回国，也不会非法滞留？
-Not need.
6.申请信里是否可以直接按实际情况说明是因为我有晚间的课程无法带孩子所以需要我妈妈帮助带孩子，
-Never say that. It is illegal for her to take care of your kid because she has no right to work in US.
还是只能说我妈妈在这儿是来旅游，因为之前我没有充分的时间陪她出去以至于需要延期继续旅游？-Yes.
非常感谢！
