1. ～（よ）うではないか (Let’s... / Shall we all...)
Explanation: Calls on or proposes that a group do something together: “Let’s... / Why don’t we...”.
✓ ～ようではないか is more formal, rhetorical, and forceful than simple ～よう and is common in speeches, appeals, and meetings.
✓ ～ようじゃないか is more conversational and can occur in everyday speech, so it is too absolute to say that the pattern is never used in daily conversation.
2. ～ことだ (You should / should not...)
Explanation: Vる / Vない + ことだ gives advice or guidance: “you should... / you should not...”.
✓ It is often used when the speaker sees the action as a good way to achieve a goal or solve a problem.
✓ The sentence ending itself is ことだ / ことです; the preceding verb may be affirmative or negative (Vないことだ).
✓ Because it can sound direct, care is needed when advising a superior, but this is a pragmatic tendency rather than an absolute grammatical prohibition.
3. ～ものだ / ～ものではない (One should / should not, as a general rule)
Vる + ものではない
Explanation: ～ものだ / ～ものではない states what is regarded as proper, natural, or socially expected: “one should... / one should not...”.
✓ Unlike ～ことだ, which often advises about a specific situation, this pattern tends to express a general norm, principle, or social expectation.
✓ It can occur in direct admonition, but may sound preachy, so the relationship with the listener matters.
4. ～ことはない (There is no need to...)
Explanation: Vる + ことはない means “there is no need to... / you do not have to...”. The speaker judges the action unnecessary in the current situation.
✓ It is often used to reassure someone or advise them not to do something unnecessary.
✓ Do not confuse it with Vないことはない, meaning “it is not that...not / it is possible to...”.
5. ～まい / ～（よ）うか～まいか (I will definitely not... / Whether to... or not)
Vよう + か + Vる + まいか
* Group 2 and 3 verbs: V ます + まい (Exception: する → するまい / すまい)
Explanation: In this lesson, ～まい expresses negative determination: “I will not / I am determined not to...”. ～（よ）うか～まいか expresses hesitation over whether to do something.
✓ ～まい also has a negative-conjecture use, “probably will not...”; distinguish the two by context.
✓ With する, both するまい / すまい occur. Group-2 verbs may also show forms such as 食べまい alongside 食べるまい.
6. ～ものか / ～もんか (Absolutely not! / No way I will...)
Explanation: ～ものか / ～もんか is an emotional, emphatic negation: “no way... / absolutely not... / how could...?”.
✓ Depending on context, it can express determination not to do something or strongly reject a claim or possibility.
✓ ～もんか is the more colloquial form. Because it is forceful, context and the relationship with the listener matter.
