短语词组短语reverse graded bedding 反序粒层理content graded bedding 含量递变层理double graded bedding 双重粒级层biogenic graded bedding 生物粒级层;[古生]生物递变层理rhythmic graded bedding 韵律性递变层理reversely -graded bedding 倒转分级层 返回 graded bedding