$1.$ Chose match$($es$)$ for each given basic$/$extended regular expression $($maybe

multiple correct matches$)$ and describe the pattern of matched string for $3),$

$4),6),11).$

Note: $1)$ to $5)$ are basic regexes;

$1)$a$($ab$)*$a$$

$($a$)$ababa $($b$)$ aaba $($c$)$ aabab $($d$)$ aabbaa $($e$)$aa

$2)$a$?[$bc$]*$

$($a$)$ abc $($b$)$ a$?[$bc$]($c$)$ a$[$bc $($d$)$ a$?($e$)$ abcbc

$3).[$nd$]*$

$($a$)$ wind $($b$)$ window $($c$)$ end $($d$)$ good $($e$)$will

$4)[$a$-$z$]+[0-9]$

$($a$)$ a$++($b$)$ aa$++($c$)6+($d$)$ a$+6($e$)$ aa$+1$

Note: $5)$ to $12)$ are extended regexes.

$5)$a$($a$|$b$)*$a$$

$($a$)$ababa $($b$)$ aaba $($c$)$ aabab $($d$)$ aabbaa $($e$)$aa

$6)[$a$-$z$](\backslash +[$a$-$z$0-9])+$

$($a$)$ x$+9($b$)$ x$+$y $($c$)1($d$)$ y $($e$)$ x$++$y

$7)$a $($bc$)*$z$$

$($a$)$azbc $($b$)$ az $($c$)$ azbcbc $($d$)$ acc $($e$)$acz

$8)$a$.*[0-9]$

$($a$)$a$|1($b$)$ a$*2($c$)$ ab$2($d$)$ abc $($e$)$aaa

$9)[$a$-$t$]+[\backslash .\backslash ?!+]$

$($a$)$bash$!($b$)$ c $($c$)$ Java? $($d$)$ python! $($e$)$c$++$

$10)[$a$-$z$]+[\backslash .\backslash ?!]\backslash$s$*[$A$-$Z$]($hint: $\backslash$s matches any whitespace characters$)$

$($a$)$o$.$ year$($b$)$ x$?$y $($c$)$ U$.$S$.($d$)$Hello$!$HELLO $($e$)$index$?$a

$11)($very$\backslash$s$)?($cool$\backslash$s$)+($good$|$bad$)$ weather$$

$($a$)$very weather $($b$)$ very cool weather $($c$)$ good weather

$($d$)$ very cool good weather $($e$)$cool bad weather

$12)-?([0-9]|([1-9][0-9]))$

$($a$)123($b$)-123($c$)-0($d$)-2\mathrm{.}2($e$)1\mathrm{.}2$

$13)-?[0-9]*\backslash .?[0-9]*$

$($a$)123($b$)-123($c$)-0($d$)-2\mathrm{.}2($e$)1\mathrm{.}2$