Show that the language A $=\{|$ R is a regular expression and there is at least one string w in L$($R$)$ such that w has $00101$ as a substring $($that is$,$ w $=$ x$00101$y for some strings x and y$)\}$ is decidable. $2.$ Show that the language L $=\{|$ M is a TM that accepts all strings of length $5\}$ is undecidable.