Give regular expressions generating the following languages

a$.\{$w$|$ w begins with a $1$ and ends with a $0\}$

b$.\{$w$|$ w contains at least three $1$s$\}$

c$.\{$w$|$ w contains the substring $0101($i$.$e$.,$ w $=$ x$0101$y for some x and y$)\}$

d$.\{$w$|$ w has length at least $3$ and its third symbol is a $0\}$

e$.\{$w$|$ w starts with $0$ and has odd length, or starts with $1$ and has even length$\}$

f$.\{$w$|$ w doesn$$t contain the substring $110\}$

g$.\{$w$|$ the length of w is at most $5\}$