כי אם בתולות מזרע בית ישראל והאלמנה אשר תהיה אלמנה מכהן יקחוThis is translated by many commentators (such as the Art Scroll Chumash) as
only virgins of the seed of Israel; but a widow who is only a widow, some Kohanim may take.This means that a regular Kohen may marry a widow even though the Kohen Gadol (high priest) may not.
However, when looking at the Hebrew, it appears as if the translation should read:
Only a virgin from the seed of Israel and a widow of a Kohen may they take.This changes the meaning of the sentence completely and appears to contradict the Torah law that a regular Kohen may marry a widow. However, I have found a possibility that allows this statement to stand as translated in the second way. A widow can either have children or not have children. If she has not had children, then she is subject to yibum (marrying her brother-in-law) or Chalitza (equivalent to divorce). For a Kohen to marry the widow of a nonKohen, she must have undergone Chalitza. By rabbinic law a woman who has gone through Chalitza is treated as if she were a divorcee and is forbidden to marry a Kohen. Thus the widow of a nonKohen must have children if she is to be allowed to marry a Kohen. However, these children are not Kohanim and are forbidden to eat terumah even though their mother (who is now the wife of a Kohen) would be allowed to eat terumah. Similarly, any children the mother would have are now Kohanim and could eat terumah.
Is this a problem? Perhaps it can be considered like a child who has an allergy and cannot eat the same food as the other children in the family. However, this really is not the same as a child can understand the necessity to stay away from some food in order to not get sick. Terumah on the other hand is a spirituel matter and the child could wind up eating it, even accidentally. The mother could wind up putting it in front of all the children who would then eat it.
We actually see this situation in parshas Emor (Vayikra 22:13)
ובת כהן כי תהיה אלמנה וגרושה וזרע אין לה ושבה אל בית אביה נכנעוריה מלחם אביה תאכל וכל זר לא יאכל בו
And a Kohen's daughter who is widowed or divorced and has no children may return to her father's house as in her youth, she may eat from her father's food, but no "stranger" (nonKohen) may eat from it.The commentaries point out that one of the reasons for this is that she could wind up feeding her children terumah. This is forbidden since they are not Kohanim. Rashi also points out, that as long as she has children who are not Kohanim, she is considered part of a family of nonKohanim. This would be the source of the rabbinic enactment describe by Yechezkel forbidding the widow of a nonKohem who has children from marrying a Kohen. This is like the enactment forbidding a Kohen from marrying a woman who has undergone Chalitzah just like he is forbidden to marry a divorcee.
This allows the sentence in Yechezkel to be read in a straight forward manner and to mean that a Kohen may only marry the widow of another Kohen.