助動詞・仮定法
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。
⚠️ひっかけ注意 — よくある失点パターン
- mustn’t（禁止） vs don’t have to（不要）を混同しない。
- may（許可/可能性）と can（許可/能力）のレジスター差に注意（正式通知や掲示は may を好む）。
- could は「過去の一般能力」には使えるが「一度限りの達成」は was able to / managed to が自然。
- should have + p.p.（〜すべきだったのに） vs must have + p.p.（〜だったに違いない）の意味差。
- If 節に would は通常置かない（丁寧依頼/仮主語など特殊用法を除く）。
- 仮定法過去は主語 I/he/she/it でも were が可（If I were you）。
- 提案系動詞（suggest/insist/demand/require/ask等）の that 節は原形（仮定法現在）。三単現 s を付けない。
- 混合仮定の時制一致（If he had saved earlier, he would be debt-free now.）に注意。
ポイント別演習
義務・助言
must / have to / should
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).
Employees ___ not disclose confidential information to third parties.
You ___ better arrive 10 minutes early for the interview.
Participants ___ have submitted their applications by yesterday.
可能性・許可
may, might（推量）/ can（能力）/ could（丁寧・可能）
It ___ rain later, so bring an umbrella.
The package ___ arrive by tomorrow, but it depends on the weather.
You ___ leave early if you finish the checklist.
When she was younger, Ms. Park ___ speak four languages fluently.
Yesterday, I ___ finish the task before 6 thanks to automation.
Mr. Kim left two hours ago; he ___ have arrived at the airport by now.
仮定法過去
If S 過去形, S would 原形
If I ___ you, I would renegotiate the scope.
If we ___ a larger venue, we could host more attendees.
If I ___ more time, I would join your workshop.
She would travel more if she ___ enough savings.
If our office ___ closer to the station, commuting would be easier.
___ I have a chance to meet the CEO, I would discuss the new strategy.
仮定法過去完了
If S had p.p., S would have p.p.
If we ___ the risks earlier, we would have postponed the launch.
She ___ the train if she had left ten minutes earlier.
If you ___ contacted us earlier, we could have shipped the order on time.
I would have attended the seminar if I ___ about it earlier.
Had they ___ the warnings, the outage could have been avoided.
The deadline was missed; if Mr. Lee ___ in charge, the project ___ on time.
提案系の原形
suggest/insist/demand that S 原形
The manager recommended that the report ___ shorter.
We insist that all attendees ___ their badges at all times.
The committee proposed that the deadline ___ extended by one week.
The board requested that the budget ___ by next Monday.
It is essential that every employee ___ the safety guidelines.
It is important that the agreement ___ signed before the meeting.