2. jess is (tall) ellie. 3. mina (happy) girl. 4. ellie (short) girl. 5. jess has got (short) hair. 6. ellie has got (long) hair than jess. 7. mina (tall) girl. 8. ellie has got (long) hair. 9. mina (tall) jess.

Сравнительная степень- добовляется "er" и than. Jess is taller than Ellie
Превосходня степень- добовляется "est" и the. Mina is the happiest girl
Определять по смыслу, тоесть
Джесс (высокая) Элли. здесь сравнительная степень.

2. Jess is taller than Ellie. 3. Mina is the happiest girl. 4. Ellie is the shortest girl. 5. Jess has got the shortest hair. 6. Ellie has got longer hair than Jess. 7. Mina is the tallest girl. 8. Ellie has got the longest hair. 9. Mina is taller Jess.