public Word(Guid id, PartOfSpeech partOfSpeech, CEFR cefr, ResourceId?pictureId)
{
Id = id;
PartOfSpeech = partOfSpeech;
Cefr = cefr;
PictureId = pictureId;
}
public Expression(Guid id, ExpressionType exprType, CEFR cefr)
{
Id = id;
ExprType = exprType;
Cefr = cefr;
}