区别就是两者都是动词lie的短语但意思是不一样的，具体的不同如下
lie flat中文意思是躺平
She injured her spine in a fall and a doctor told her to lie flat on her back for a month so it can mend.
lie down中文意思是躺下
I just lie down, the telephone rang.
区别就是两者都是动词lie的短语但意思是不一样的，具体的不同如下
lie flat中文意思是躺平
She injured her spine in a fall and a doctor told her to lie flat on her back for a month so it can mend.
lie down中文意思是躺下
I just lie down, the telephone rang.
