L1 = ['Hello', 'World', 18, 'Apple', None]
L2=[s.lower() for s in L1 if isinstance(s,str)==1]
# 测试:
print(L2)
if L2 == ['hello', 'world', 'apple']:
print('测试通过!')
else:
print('测试失败!')
if isinstance(s,str)==1 可以进一步简化为 if isinstance(s,str)
谢谢
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做回自己ZXH
L1 = ['Hello', 'World', 18, 'Apple', None]
L2=[s.lower() for s in L1 if isinstance(s,str)==1]
# 测试:
print(L2)
if L2 == ['hello', 'world', 'apple']:
print('测试通过!')
else:
print('测试失败!')