A．Subjective.
B．Objective.
C．Ambiguous.
D．Changeable.

A．They focus on environmental issues.
B．They focus on people's mental health.
C．They tell people how to be positive.
D．They tell people how to be confident.

A．Human brains tend to store bad memories.
B．Human brains search for a memory not long ago.
C．Responses are based on a reference memory.
D．New information is memorized better than old ones.