C
固定用法：tell sb not to do sth告诉某人不要做某事
forget to do sth 忘记去做某事I didn’t know if _____ was around and I felt ______. A. someone, frighten B. someone, frightened C. anyone, frighten D. anyone, frightenedfeel 后面是加动词原形吗feel 是系动词，后接形容词作表语，故排除A与C，根据‘IF ’ 是否，可知句子是疑问，再排除B，故正确答案是D。