You may assume that a and $b$ are integers and $-128a,b127.$ From the list below, select every sentence that must be true.

A$.a-b=a+(-b).$

B$.1$ and $2$ are binary digits.

C$.{10}_{10}-1_{10}=1_{10}.$

D$.{10}_{16}-1_{16}=F_{16}.$

$E.$ If then to find the $8-$bit two's complement of $a$ we write the $8-$bit binary representation of $a,$ flip the bits and add $1$ in binary.

E$.$ If $a0,$ then to find the $8-$bit two's complement of $a$ we write the $8-$bit binary representation of $a,$ flip the bits and add $1$ in binary.