我2017年3月1号来马里兰，I94 8月底过期，5月底我申请了B2转F1，7月20又申请了延期，现在除了两个 receipt 没有任何消息，学校让我再申请延期。请问我这种情况是不是很危险啊，B2可以申请两次延期吗，尤其是我的第一次延期还没收到消息的情况下。
My client had the exact same issue as you. She was admitted to the United States on a B2 Visa from June 18, 2014 until December 17, 2014. We timely filed an I-539 on December 15, 2014, requesting an extension of the tourist visa until June 15, 2015. As of June 2015, no decision was made on the I-539. On June 15, 2015, I timely filed a second I-539 with a copy of the receipt for the first I-539. On November 17, 2015 I received two approval notices in the mail, one for the first I-539 and one for the second I-539. Therefore, you should timely submit a second I-539 with a copy of the receipt for the first I-539.
然而，一般来讲 B1/B2 签证入境最多给6个月、单次停留最多1年，多次申请延期、总停留期限超过1年的情形比较少见，很难说 USCIS 批准的机率有多大，建议务必搞清楚逾期逗留甚至非法停留的后果，参见这篇文章。