两个都可以.词典里有这两句话make everyone at their easeeverybody bought their own luncheveryone should do his best to serve the people另外their有个用法,代替单数不定代词,意思是his ,herlet us give everyb...Everyone loves ( )mother(s).如果用their,mother变复数吗？PS你那是什么字典？商务印书社简明英汉词典词典里没有举可数名词的例句，但从以往的反义疑问句的类似题句中，以复数看。