#4　形式主語を用いたIt is ～ to doとIt is ～ that …は書き換え可能か？

難易／安全・危険／快・不快　を表す形容詞　→It is ～ to doのみ使用可能
・The problem is easy to solve.「問題を解決するのは簡単だ」
= It is easy to solve the problem.
* It is easy that you solve the problem.

・It is important to learn English.「英