-*- coding: utf-8 -*-

f=open('scores.txt')
lines=f.readlines()

f.close()

results=[]

for line in lines:
data=line.split()

sum=0
for score in data[1:]:
    sum+=int(score)
result='%s\t:%d\n'%(data[0],sum)
results.append(result)

output=open('results.txt','w')
output.writelines(results)
output.close()

必须越界，分隔的方法有问题，这是你的方法截下来的，
['刘']
['备']
[]
['2']
['3']
[]
['3']
['5']
[]
['4']
['4']
[]
['4']
['7']
[]
['5']
['1']

因为你拿到的lines已经是一个字符串了，所以当你切割的时候，只能继续细分，你可以直接用lines.split()