A man witnessed ________ the young lady risk ________ across the road and knocked down by a passing car．A.seeing：walkingB.to see：to walkC.to having seen：walkingD.to have seen：to walk
网友回答
C解析witness to sth．意为“为……作证，证明……”；risk doing sth．是固定短语，意为“冒险做某事”。