题目内容：
When Mary discovered how treacherous the streets could be，she demanded that her boys stay close to her in the church gym and youth center，and the boys were as good as gold，listening to every word she says．
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答案解析：
单选题：When Mary discovered how treacherous the streets could be，sh
- 题目分类：3级
- 题目类型：单选题
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