The document discusses the differences between should/shouldn't and must/mustn't. Should and shouldn't express duty, necessity, or advice, with should being weaker than must. Must and mustn't express obligation or prohibition, with mustn't prohibiting an action. The positive forms of should and must are used with he, she, it plus the base verb form. The negative forms are shouldn't and mustn't plus the base verb form. Questions are formed by placing should/shouldn't or must/mustn't before he, she, it plus the base verb form.

1. Should/ Shouldn’t Must/ Mustn’t

2. SHOULD/SHOULDN’T Duty , necessity (weaker than must), advice : He should get up early. You shouldn’t spend so much money.

3. MUST/MUSTN’T Obligation: Students must wear uniform. Prohibition : You mustn't speak during the exam.

4. Positive Form: I You We They should + V 1 He must + V 1 She It

5. Negative Form: I You We They shouldn’t + V 1 He mustn’t + V 1 She It

6. Question Form: I You We Should/Shouldn’t They + V 1 Must /Mustn’t He + V 1 She It