Explanation: Apparently Peter can only use 1 borrowed ability/power at a time. Since he was using Ted Sprague's radioactive ability he probably couldn't use Nathan's power of flight. Edit
S 4 : Ep 18
Aired 2/8/10
S 4 : Ep 17
Aired 2/1/10
S 4 : Ep 16
Aired 1/25/10
S 4 : Ep 15
Aired 1/18/10
User Score: 872
User Score: 1326
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User Score: 162
User Score: 160
User Score: 149
User Score: 129
User Score: 114
User Score: 114