the doctor was seen （comforting ）the patient.

see 有两个句型
see sb do sth 看到某人做了某事
被动形式是 sb be seen to do sth 强调看了做事的过程
see sb doing sth 看到某人正在做某事
被动是 sb be seen doing sth 看到某人正在做某事 这道题强调看到医生正在安慰病人哈
还有 hear watch 等
你记住就好了哈