求帮助 1st cs phd ad@CSM

1st ad cs @colorado school of mines. 我不确定是不是offer, 就暂且认为是ad吧. 上个月面试完, 等了将近一个月, 小年, 也就是昨天收到老师的邮件,写到 right now i have decided to make an offer(个人批注: 不知道这里的offer指的是ad还是给钱) to you. Would you like to accept it? If yes, I need have one more talk with you. Note that, my offer at this stage is not official. But if you accept it, I will push the department to send the official offer to you as soon as possible. 现在纠结的是这个学校是我申请的排名最低的保底学校, 过几天我还有IUB的面试, 我想着尽量的拖着他, 看看其他学校的结果怎样, 但是我又怕如果我发邮件告诉他需要考虑时间, 他会不会直接把这个所谓的offer给其他人 我不知道该怎么回复他了. 还请各位给些建议! 真心感谢. 也祝愿其他人offer多多.