[填空题]
Jennifer is about to take three mon9aae*;ij36kmt pblkk f5* /lfw+:exams in order: Mathematics, Chemistr, 0x5vhmpql0 zj3c1wuy and Biology. Based on what she has learned and practiced, she estimates that the probabilities that m01 ph0 c,vxquwzjl53she will pass Mathematics, Chemistry and Biology exams are 0.8,0.6 and 0.7 , respectively. Assuming that the probability of Jenifer being passing an exam is independent of the others, find the probability that
1. she will pass all three exams;
2. she will pass only one of the exams;
3. she will pass the last two exams given that she doesn't pass the first exam;
4. she will pass at least one exam.
