Jobin's Tiredness: Selecting the Correct Modal Verb

The question asks us to choose the correct word to complete the sentence: "Jobin has been working all day. He _______ tired." We need to find the word that best expresses the logical conclusion based on the fact that Jobin worked all day.

Understanding Modal Verbs and Logical Conclusions

The first part of the sentence, "Jobin has been working all day," provides a reason or evidence. The second part, "He _______ tired," needs a word that connects this evidence to a conclusion about his state. Modal verbs like 'can', 'will', 'shall', and 'must' are often used to express different degrees of certainty or possibility.

• 'Must be' is used to express a strong logical conclusion or certainty based on available evidence. Since working all day usually makes someone tired, it's highly probable that Jobin is tired.
• 'Can be' suggests a possibility, but it's weaker than what the situation implies. Working all day doesn't just make it *possible* for him to be tired; it strongly suggests it.
• 'Will be' and 'Shall be' typically indicate future certainty or predictions. While he might be tired in the future, the sentence structure suggests a conclusion about his current state resulting from the day's work.

Analyzing the Options

Let's look at why 'must be' is the most appropriate choice:

• Option 1: can be - This implies possibility. It's possible Jobin is tired, but the context suggests a stronger likelihood.
• Option 2: will be - This focuses on the future. The sentence implies a conclusion about Jobin's current state based on his recent activity.
• Option 3: shall be - Similar to 'will be', this is generally used for future actions or formal contexts and doesn't fit the sense of logical deduction here.
• Option 4: must be - This perfectly fits the context. The fact that Jobin has been working all day leads to a strong, logical conclusion that he is tired.

Final Conclusion

The phrase "working all day" serves as evidence. The modal verb 'must be' is used to draw a strong, logical conclusion from this evidence. Therefore, the completed sentence reads: "Jobin has been working all day. He must be tired." This indicates a high degree of certainty based on the given information.