deep down in the earth for thousands of years the dead forest has rotted away and become

问题补充：

deep down in the earth for thousands of years, the dead forest has rotted away and become coal．

A. Having buried

B. Being buried

C. Buried

D. To be buried

答案：

A. Having buried

B. Being buried

(答案→)C. Buried

D. To be buried

解析：句意：被埋在了泥土中数万年，死亡的森林已经腐烂变成了煤。动作bury与其逻辑主语the dead forest是被动关系，故用过去分词作原因状语，选C。