volcanoes now for many years, I am still amazed at their beauty as well as their potential to cause great damage.
A. Studied
B. To study
C. Having studied
D. Studying
网友回答
A. Studied
B. To study
(答案→)C. Having studied
D. Studying
解析：句意：已经研究火山爆发这多年了，我仍然惊奇它们的美丽和它们引起大的威力的潜力。因为整个句子已经有谓语动词，所以空格处应该用非谓语动词，因为for many years说明study的动作先于谓语动词的动作发生，故用完成时，故选C。