pandas怎么修改部分?jǐn)?shù)據(jù)但輸出所有的值

這是df的數(shù)據(jù)

df
Out[86]: 
        one       two     three
A -0.709805  1.070332  0.931865
B       NaN       NaN       NaN
C  2.370934 -0.688606       NaN
D  0.868554 -1.443167       NaN
E -0.668985 -1.378245 -1.302251

我想要只替換掉one two兩列的nan，然后其余的原樣輸出

書上給的例子 df[['one','two']].replace(np.nan,'hello')

Out[88]: 
        one       two
A -0.709805   1.07033
B     hello     hello
C   2.37093 -0.688606
D  0.868554  -1.44317
E -0.668985  -1.37825

由于有df[['one','two']]提前進行了列篩選，導(dǎo)致最后結(jié)果雖然只替換了one two兩列，但也只輸出了one two兩列
想問
怎么在僅對兩列替換的同時，把四列全部顯示出來