$m^{\times}\left(A\right)=\inf\left(\sum_{ }^{ }l\left(I_n\right):\ A\subseteq\cup I_n\right)\$ is definition of

If $\mu\left(\phi\right)\ =0$  then  $\mu$  can be____

If A and B are two sets with m*(A)=0 then

If A and B are two sets, with A $\subseteq$  B, then

If A is countable set then