题目

阅读下面材料，根据其内容和所给段落开头语续写两段，使之构成一篇完整的短文。Mary waited anxiously for her turn in the empty dressing room. Never had she been so nervous before. This competition was of vital importance to her comeback. If I can win today, she said to herself, I can dance on the national stage next month. Three months ago, her left arm was seriously injured in a car accident. After the medical treatment, she began to recover slowly. She practiced over and over again in order to regain her dancing skills. Hi,Mary, in rushed her friend Jessica. H如图，开始时，桶1中有a L水，t分钟后剩余的水符合指数衰减曲线y1=ae－nt,那么桶2中水就是y2=a－ae－nt,假设过5分钟时，桶1和桶2的水相等，则再过_________分钟桶1中的水只有.