They often play chess after they have had supper.这里 have had supper.怎么理解They often play chess after they have had supper.这里 have had supper.怎么理解,是不是从句的发生时间在主句之前,用完成态,这里的现在完成时态是不是根据主句的时间,如果主句是过去,从句过去完成时态请问另外两种情况怎么处理,从句的发生时间在主句之后或者从句的发生时间和主句并列

They often play chess after they have had supper.这里 have had supper.怎么理解
They often play chess after they have had supper.
这里 have had supper.怎么理解,是不是从句的发生时间在主句之前,用完成态,这里的现在完成时态是不是根据主句的时间,如果主句是过去,从句过去完成时态
请问另外两种情况怎么处理,从句的发生时间在主句之后或者从句的发生时间和主句并列