动脑筋算一算。+Q7I,O'\-k2~9_*M
（1）+Q7I,O'\-k2~9_*M
5v:a4N6i.Q1`4J.v5I+Q7I,O'\-k2~9_*M
（2）+Q7I,O'\-k2~9_*M
)_9Y5\3w.z*\+y.i5x+Q7I,O'\-k2~9_*M