Invalid marriage refers to the combination of men and women who lacks the conditions for the establishment of a marriage. It includes invalid marriages that violate the legal conditions and marriages that violate the legal procedures. The legal conditions for marriage are: ① both men and women must be fully voluntary; ② must reach the legal age of marriage; Comply with monogamy. The marriage process is roughly divided into three parts: application, review, and registration. According to the above definition, which of the following is invalid marriages? ['Two elderly people in their 70s lost care of their widows at the same time, and then became husbands and wives after registration.', 'Kobayashi and the three sisters are in love, but both parents are opposed to the relationship, so the two resolutely elope to live a de facto husband and wife life.', 'A 50-year-old middle-aged painter married a 27-year-old young woman as a wife and lived a happy life.', "Brother Zhang and Sister Feng's marriage was matched by their parents, but also with their personal consent."]