Week # $7,$ homework exercises, due by $11$:$30$ April $26$th

Give context$-$free grammars that generate the following languages. Note that you just need to solve one of questions $3$ and $4.$

$(5$ points$)$ All regular expressions on the alphabet $=\{a,b\}.$ What is the leftmost derivation for $a^{**}b?$

$(5$ points$)$ does not have $3$ consecutive $0$ s$.$