Participants were balanced across the three groups for age, sex, educational back-ground, severity and duration of depression, and use of antidepressants.
这三组参与者在年龄、性别、教育背景、抑郁症的严重程度和持续时间以及抗抑郁药物的使用上保持平衡。
2
By talking to the other parents, parents can know a lot about the other family's back-ground, even if they don't meet the kid.
即使没有见到孩子，但通过与对方父母交谈，他们也可以很好地了解对方的家庭背景。
3
He was back on familiar ground , dealing with the customers.