2个小问题

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1.It marks the passage of one entering into adulthood and gaining its freedoms.
　　它标志着一个人已经成年并获得了自由。
　　问题：the passage是啥意思，entering into...是用来修饰the passage of one的吗？
　　
　　2.Going off to college is normally the first time they will live away from their family.
　　上大学一般是他们第一次离开家。
　　问题：go off是啥意思？