It's not easy having a brother who is retarded. But we are trying to make it into a good thing instead of a bad thing."" That's Sarah, who's ""7 and ¬ years old"" to retarded Andy's five, and well primed to explicate the special resentments, humiliations, and satisfactions of being in her difficult position. And, to the accompaniment of static, gray-toned pencil drawings mostly illustrative of her moods, that's about all she does--with a minimum of carry-over from one page's confidences to the next. A child who's similarly situated might recognize a kinship with Sarah and be encouraged to acknowledge his/her own mixed feelings; but in the virtual absence of dramatic shape or incident, others are likely to find it arid and uninvolving.