Consider the sets `phi, A={1,2}, B={1,6,7}, C={1,2,3,4,5}`. Insert the symbol `subset or cancel(sub)` between each of the following pair of steps.
(i) `phi"__ "B`
(ii) `A"__ "C`
(iii) `A"__ "B`
(iv) `B"__ "phi`

Explanation

(i) `phi"__ "B, phi` is subset of every set
(ii) `A"__ "C, 1, 2 in A" also "1,2 in C`
(iii) `A"__ "B, 2 in A" but " 2 in B`
(iv) `B"__ "phi, phi` is empty set has no subset.