Ответ:

a) One-syllable adjectives ending in two consonants, add -er.

b) One-syllable adjectives ending in two vowels and a consonant, add -er.

c) Most adjectives ending in a vowel and a consonant,  double the consonant and add -er.  

d) Most adjectives with more than one syllable use more.

e) Adjectives of one and two syllables ending in y usually change y to i and add -er.

f) Short adjectives ending in e, usually add -r.

Объяснение:

Примеры из Упр. 1, иллюстрирующие указанные правила:

a) light - lighter

b) cheap - cheaper  

c) big - bigger  

d) common - more common  

e) noisy - noisier

f) safe - safer