L=['Hello','World',18,'Apple',None]
L2=[s.lower() for s in L if isinstance(s,str)==True]
print(L2)
if L2==['Hellow','World','Apple']:
print('测试通过')
else:
print('不通过')
L=['Hello','World',18,'Apple',None]
L2=[s.lower() for s in L if isinstance(s,str)==True]
print(L2)
if L2==['Hellow','World','Apple']:
print('测试通过')
else:
print('不通过')