助動詞のニュアンス差と If 構文を整理。
文脈に応じた助動詞・時制の選択ができる。
義務（強）
助言・忠告
許可
可能性・推量
能力
過去の推量
must / have to / should
コツ: should は助言、must は強い義務。have to は外的規則・制度による義務で頻出。
You ___ submit the report by 5 p.m.; it’s a hard deadline.
To avoid burnout, you ___ take short breaks every hour.
All visitors ___ wear a badge while on site (company policy).
may, might（推量）/ can（能力）/ could（丁寧・可能）
コツ: 許可（You may…）/能力（can）/推量（may/might）を文脈で切り分ける。
It ___ rain later, so bring an umbrella.
You ___ leave early if you finish the checklist.
Yesterday, I ___ finish the task before 6 thanks to automation.
If S 過去形, S would 原形
コツ: 現在の非現実。be 動詞は were を推奨（If I were you）。
If I ___ more time, I would join your workshop.
She would travel more if she ___ enough savings.
If I ___ you, I would renegotiate the scope.
If S had p.p., S would have p.p.
コツ: 過去の事実と反対。倒置（Had + S + p.p., ...）も頻出。
If we ___ the risks earlier, we would have postponed the launch.
She ___ the train if she had left ten minutes earlier.
Had they ___ the warnings, the outage could have been avoided.
suggest/insist/demand that S 原形
コツ: that 節の動詞は三単現の s を付けない（原形）。受動なら「be + p.p.」。
The manager recommended that the report ___ shorter.
We insist that all attendees ___ their badges at all times.
The board requested that the budget ___ by next Monday.