Reviewing comparatives -- 比較級を復習 (updated)

Comparative grammar has two parts, the "more" part and the "than" part.
比較級の文法に二つの部分があります。つまり、 "more" の文と "than" の文です。

"More" means a greater number or measure.
"More" とは多い方の数や量を示している。「もっと」と訳して良い。

"Than" indicates the object of comparison, the lesser part.
"Than" とは比べられた方です。つまり、数や量の少ない方です。「より」と訳して良いけど、置く位置が日本語と逆です。

• more cheese もっとチーズ
• more cheese than sausage ソーセージより、もっとチーズ

Let's put those in sentences:

• Please put more cheese on my pizza. 私のピザにチーズをもっと多くつけてください。
• I want more cheese than sausage. チーズをソーセージよりも多くつけてほしい。

"More" can be used with adjectives:

• more tall もっと（背の）高い
• more short もっと（背の）短い
• more heavy もっと重たい
• more light もっと軽い
• more interesting もっと興味を起こす（興味有る）
• more fun もっと面白くて楽しい
• more funny もっと可笑しくて面白い
• more disgusting もっと嫌でむかつく

And also with adverbs:

• more quickly もっと素早く
• more slowly もっとゆっくりと
• more carefully もっと念を入れて

Many relatively short adjectives can be combined with "more":

• taller
• shorter
• heavier
• lighter
• interestinger (too long and clumsy)（長くて言いにくい）
• funner (*Preferred form is "more fun".) （普段の形は "more fun" です。）
• funnier
• disgustinger (too long and clumsy)（長くて言いにくい）
• quicklier (adverbs don't) （副詞はできません。）
• quicker もっと素早い
• slowlier (adverbs don't) （副詞はできません。）
• slower もっとゆっくりした
• carefullier (adverbs don't) （副詞はできません。）
• carefuller (too long and clumsy)（長くて言いにくい）
• more careful もっと注意深い

The shorter form is usually preferred. In the case of "fun", there can be confusion with "funny", so "more fun" is usually preferred.

大抵は短い方が優先されるけど、"fun" の場合は "funny" との矛盾が生じるので "more fun" の方を普段に使っています。

When we need to compare things, we add "than (something)".

比べるときは "than (何とか)" を取り付けます。

• taller than Mount Fuji 富士山よりも高い
• shorter than my thumb ボクの親指よりも短い
• heavier than water 水よりも重たい
• lighter than air 空気よりも軽い
• more interesting than Wikipedia ウィキペディアよりも面白い
• more fun than a barrel of monkeys バレルに入れたお猿さん一族よりも楽しく面白い
• funnier than Joel's jokes ジョエルの冗談よりも可笑しくて面白い
• more disgusting than natto 納豆よりも嫌でむかつく
• more quickly than a gnat jumps ブトが跳ぶよりも素早く
• quicker than a bolt of lightening 落雷が落ちるよりも早い
• more slowly than a glacier flows 氷山が流れるよりも遅く
• slower than a snail カタツムリよりも遅い
• more carefully than a surgeon works 外科が手術を行うよりも念を入れて
• more careful than Doctor Jack ジャック先生よりも注意深く

Comparative phrases may or may not be used as a unit.

比較文は一塊として使うこともあるけどバラバラになる場合もあります。

• Joel is not taller than Mount Fuji.
• Your pencil is shorter than my thumb.
• How can a ship that is heavier than water float?
• Balloons filled with helium are lighter than air.
• I can think of something more interesting to do than read Wikipedia .
• This new video game is more fun than a barrel of monkeys.
• Joel's website is no funnier than his jokes.
• Junko says there are many things more disgusting to eat than natto.
• When the teacher came in, Jiro jumped up more quickly than a gnat.
• Bolt is quicker than a bolt of lightening.
• Joel's English classes flow more slowly than a glacier.
• My new car is slower than a snail.
• He cut into the circuit board more carefully than a surgeon.
• It may be hard to find a more careful doctor than Doctor Jack.

"Less" uses similar grammar to "more".

"Less" は "more" にちなんだ利用法です。

• less tall
• less short
• less heavy
• less light
• less interesting
• less fun
• less funny
• less disgusting
• less quickly
• less quick
• less slowly
• less slow
• less carefully
• less careful

Again, finally, the comparative forms of "good", "well", and "bad" are irregular. "Good" and "well" become "better", and "bad" becomes "worse":
また、最後に、"good"、 "well"、 及び "worse" の比較級が不規則です。"Good" も "well" も "better" に、 "bad" は "worse" に変わります。

• I did well on the test. But my friend John did better than I. My friend Henry did worse.
• The tuna sushi is good. The squid sushi is even better. 
• Which did she think was worse, the natto donuts or the natto cheesecake?
• She said she thought the natto cheesecake tasted worse than the natto donuts.

That makes a pretty complete list of examples.
これで例文を充分に並べたと思います。