write each of the following using ‘if and only if’ :
(i) In order to get A grade, it is necessary and sufficient that you do all the homework regularly.
(ii) If you watch television, then your mind is free, and if your mind is free, then you watch television.
(i) You get an A grade if and only if you do all your homework regularly.
(ii) You watch television if and only if your mind is free.