如图所示,请在图中无线电广播的接收过程图的空格中填入恰当的器材和元件名称.
发射:话筒把声音信号转换成音频电信号;通过调制器把音频电信号加载到高频电磁波上;通过天线把载有音频电信号的电磁波发射出去.
接收:天线接收电磁波;调谐器选出某一频率的电磁波;从高频电磁波通过检波器取出音频电信号,放大后送到扬声器;扬声器把音频电信号转换成声音.
故答案为:
①在人们的实践中不断发展
②是主观与客观具体的历史的统一
③在认识过程中不断被推翻
④是客观与主观具体的历史的统一
用所给单词的适当形式填空
①He was one of the best____ in yesterday’s football match.(play)
②More and more____ have come to visit China over these years.(foreign)
③She hoped that her son would become a____.(music)
④The teacher was pleased with her____.(honest)
⑤The mother didn’t know why her daughter was crying____.(noise)