下列代码的执行结果是？ （ ）
mylist=[' Failure' , ' is' , ' the' , ' mother' , ' of' , ' success' ]
for x in mylist[: ]:
if len(x) <=3:
mylist. append(x)
print(mylist)
[' Failure' , ' is' , ' the' , ' mother' , ' of' , ' success' ]
[' Failure' , ' is' , ' the' , ' mother' , ' of' , ' success' , ' of' , ' is' ]
[' Failure' , ' is' , ' the' , ' mother' , ' of' , ' success' , ' is' , ' of' ]
['Failure','is' ,'the' ,'mother', 'of' ,'success', 'is' ,'the' ,'of' ]