It is one of the great unsolved mysteries of this century.这是本世纪尚未解开的大奥秘之一。
It is one of the great unsolved mysteries of this century.
这是本世纪尚未解开的大奥秘之一。
something that is difficult to understand or to explain 神秘的事物；不可理解之事；奥秘:
