___how the splendid Maya Culture disappeared all of a sudden from the earth, it remains a mystery hard to solve.（ ）
A.In turn
B.As to
C.Thanks to
D.As a rule
正确答案是B
___how the splendid Maya Culture disappeared all of a sudden from the earth, it remains a mystery hard to solve.（ ）
A.In turn
B.As to
C.Thanks to
D.As a rule
正确答案是B