题目

如图，一艘核潜艇在海面下500米A点处测得俯角为30°正前方的海底有黑匣子信号发出，继续在同一深度直线航行3000米后再次在B点处测得俯角为60°正前方的海底有黑匣子信号发出，求海底黑匣子C点处距离海面的深度？（保留根号） 答案：没有感恩就没有真正的美德( No thanksgiving would be no virtue)。如今社会上一些人缺乏感恩之心，少数人甚至在父母年老体弱时都不愿意赡养。请结合自己的实际，谈几点父母值得你感恩的地方，以及将来你会做些什么来报答父母的养育之恩。1.短文的开头已给出，但不计入总词数。2.100词左右。(感恩: thanksgiving)Not only do our parents give us life, but they also give us endless love and support, always sharing our happiness and sorrow.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________