Match NaN's in one Matrix to another

Consider 2 matrices

A = [1, 2, 3, 4;
     5, 6, 7, 8]

B = [NaN  NaN  1    1;
     NaN    1  1  NaN]

How can

C = [NaN NaN 3 4;
     NaN 6 7 NaN]

I can do this for an individual row or column but can't get it to work for matrix. Thanks in advance for any help

Answer 1

[the cyclist]

C = A;
C(isnan(B)) = NaN