1. Small-smaller-the smallest.
Tall-taller-the tallest.
Old-fashioned - more old-fashioned - the most old-fashioned.
Messy-messier-messiest.
Light - lighter - the lightest.
Clean - cleaner - the cleanest.
Colorful - more colorful - the most colorful.
Comfortable - more comfortable - the most comfortable.
Large - larger - the largest.
Modern - more modern - the most modern.
Bad - worse - the worst.
Thin - thinner - the thinnest.
Fat - fatter - the fattest.
Good - better - the best.
2. 1) more interesting.
2) more modern.
3) the most modern.
4) the most important.
5) more beautiful.
6) smaller.
7) cheaper.
8) bigger.
9) noiser.
10) the oldest.
3. 1) The newspaper is more interesting than the book.
2) This house isn't more modern than that one.
3) His flat isn't as comfortable as mine.