. If any of them had been the subject of a questionable betrothal or divorce, the co-wives require chalitzah but may not be taken in yibum. How is it that the betrothal was in question? [If] he threw the betrothal to her, and there is a doubt as to whether it was closer to him or closer to her —- this is a questionable betrothal. [How is it that] the divorce was in question? [If] he wrote [a bill of divorce] in his own hand but without witnesses, or with witnesses but without a date, or with a date but with only one witness —- this is a questionable divorce.