how are you all keeping?后面加all keeping是为什么?怎么讲?

能说一下这句话的场景吗?MRS.JOHNSON: Was he absent from school last week?MRS.WILLIAMS:Yes, he was. He was absent on Monday,Tuesday,Wednesday and Tuesday. How are you all keeping?MRS.JOHNSON: Very well, thank you.how are you all keeping的意思是，你们身体都好么? 这句话是口语上用于表达问候的，相似的问候语有：类似的问候语： Are you better? Are you feeling better now? Are you well? How are things going with you? How are you doing? How are you keeping? How is everything at home? How was your weekend? What are you doing there days?