a. (general / mixed)

source: Practice English with Paul              2015年7月21日

Comparatives and superlatives
source: British Council | LearnEnglish

Making comparisons
source: British Council | LearnEnglish

Comparative and Superlative Adjectives
source: autoenglish

Comparative and Superlative Adjectives
source: TeacherPhilEnglish

How to use comparatives and superlatives
source: BBC Learning English       2015年9月22日
For extra comparative and superlative materials http://www.bbc.co.uk/learningenglish/...

Basic Adjective Comparisons
source: Learn English with EnglishClass101.com       2017年10月27日
Find out more about this lesson: https://goo.gl/eHUiKQ