题目

Although I love my life, it hasn’t been a lot of fun as I’ve been ill for 28 years.Music has always been a great love of mine and, in my 20s, when my _______ was more manageable, I _______ ten years as a professional singer in restaurants, playing and singing folk songs. _______ that was years ago and times have changed. _______ I live with my mother on a country farm.Two years ago, I decided that I would need to have some kind of extra work to _______ my disability pension (残疾抚恤金). _______ I needed to sleep in afternoons, I was limited in my _______. I decided that I would consi 声音在海水中的传播速度是1530 m/s，为了开辟新航道，某科学探测船装有回声探测仪，探测水下有无暗礁，如图所示，探测船发出的声音信号经0.6 s被探测仪接收到． (1)探测船发出的声音为了有更好的回声效果，最好用什么声波？为什么？ (2)估算出海底障碍物到探测船舱底的距离是多少？ (3)若探测船在海上航行时，轮船上的一位气象学家将一只氢气球凑近耳朵听了听，马上向大家发出紧急报告：“海上风暴即将来临”．就在当天夜里，海上发生了强烈的风暴，一只氢气球怎么能预报海上的风暴呢？试分析气象学家判断风暴的物理学依据是什么？