If we have in certain norm 1). $g_j(x) \rightarrow h(x), j\rightarrow\infty$ and 2). $ f_{ij}(x)\rightarrow g_j(x), i\rightarrow \infty, \forall j$ , then we can choose a subsequence $\{f_{ij_{(i)}}, i=1,2,...\}$ from $\{f_{ij}, i=1,2,...;j=1,2,...\}$ such that $f_{ij_{(i)}}\rightarrow h, i\rightarrow\infty$, in that norm sense. And it's just a trivial matter of triangle inequality. (I leave some freedom for function definition, so that more examples or counterexamples can be taken into account.) Now my question is: What if the convergence is in pointwise sense? Can we still do that? namely, if $g_j(x) \rightarrow h(x), j\rightarrow\infty$ pointwisely,and if $ f_{ij}(x)\rightarrow g_j(x), i\rightarrow \infty, \forall j$ pointwisely, can we find a subsequence $f_{ij_{(i)}}$ from $f_{ij}$ such that $f_{ij_{(i)}}\rightarrow h, i\rightarrow\infty$ pointwisely? I constructed a counterexample which seems to be complicated. I wonder if there is any easy answer. Thanks.