[填空题]
Jennifer is about to take three e7 yqcdo.h;) y- (fontw2cbulqj(jq4.xams in order: Mathematics, Chemgth2ws 2q xoi-;5gy3wistry and Biology. Based on what she has learned and practiced, she estimates that the probabilities that she 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 w25;qogs2hg -y3tw xi 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.
