问答题
化石保护，化石的分类与挖掘
问答题
procedure
问答题
trace fossil
问答题
organism is buried rapidly
问答题
mineral soil filled inside the fossil
问答题
buy fossil in shops and exhibitions
问答题
big fossil is expensive
问答题
Recorder
问答题
taking photos
问答题
Soft sediment
问答题
Delicate fossil