Verbs: Modals

He should have informed the teacher before leaving.

Step 1: 'Should have + past participle' is used to talk about something that was the right thing to do in the past, but was NOT done. Step 2: 'He should have informed the teacher before leaving' — uses the past participle 'informed', which is grammatically correct. Step 3: 'You should have come to the party tomorrow' is wrong because 'tomorrow' refers to the future — 'should have' is used for past situations only. Step 4: 'She should have go' is wrong because after 'have', we need the past participle 'gone', not the base form. Step 5: 'Should have can' is incorrect — you cannot use two modals

May you live a long and healthy life!

Step 1: 'May' has several uses — permission, possibility, and wishing. Step 2: When 'may' is used to express a wish, the sentence begins with 'May + subject + verb' and usually ends with an exclamation mark (!). Step 3: 'May I use your phone?' — here, 'may' is used to ask for permission. Step 4: 'She may be in the library' and 'It may rain today' — both use 'may' to express possibility. Step 5: 'May you live a long and healthy life!' is a good wish expressed using 'may', and it ends with an exclamation mark. This is the correct answer.

I could drink a whole bucket of water right now.

Step 1: Understand the difference between 'could' and 'could have'. Step 2: 'Could + base verb' refers to the present moment or a general situation. Example: 'I could eat dozens of chapatis right now.' Step 3: 'Could have + past participle' refers to some moment in the past. Example: 'I could have eaten dozens of chapatis (at that time).' Step 4: 'I could drink a whole bucket of water right now' uses 'could + drink' and includes 'right now', confirming it refers to the present. Step 5: 'I could have drunk' would refer to the past. 'I could drunk' is grammatically incorrect. The correct answer

Ought to

Step 1: Different modals carry different shades of meaning. Step 2: 'Ought to' conveys the same general idea as 'should' (advice/suggestion) but carries an extra sense of moral duty or obligation. Step 3: Example: 'You ought to take care of your old parents' — this is not just advice, it suggests a moral responsibility. Step 4: 'Will' is for future actions or promises. 'Can' is for ability or possibility. 'May' is for permission or possibility. Step 5: None of the other options convey moral duty. 'Ought to' is specifically noted for expressing what is morally right to do. The answer is C.