题目内容：
According to the second paragraph, dreams_______.
A． arealways about the day's events, sorting out them one by one A．are always about the day's events, sorting out them one by one
B． areprimarily meant to relieve the stress of the day
B． are primarily meant to relieve the stress of the day
C． areonly important at the stage just before you wake up
C． are only important at the stage just before you wake up
D． movefrom different stages, each with different functions
D． move from different stages, each with different functions
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