Classify into monomials, binomials and trinomials:

(i) {tex}4y – 7x{/tex}

(ii) {tex}{y^2}{/tex}

(iii) {tex}x + y – xy{/tex}

(iv) {tex}100{/tex}

(v) {tex}ab – a – b{/tex}

(vi) {tex}5 – 3t{/tex}

(vii) {tex}4{p^2}q – 4p{q^2}{/tex}

(viii) {tex}7mn{/tex}

(ix) {tex}{z^2} – 3z + 8{/tex}

(x) {tex}{a^2} + {b^2}{/tex}

(xi) {tex}{z^2} + z{/tex}

(xii) {tex}1 + x + {x^2}{/tex}