In this English grammar error spotting question, identify the part of the sentence that is grammatically incorrect in: "His friends feel that he will be suspended unless he does not report for duty immediately."

Introduction / Context:
This question checks understanding of conditional clauses and negative structures in English. The sentence is "His friends feel that he will be suspended unless he does not report for duty immediately." Learners must decide which part contains an error. Such questions highlight common mistakes involving double negatives and the correct use of "unless" and "if". Mastering these patterns is important for clear, correct expression in both spoken and written English, especially in formal and exam contexts.

Given Data / Assumptions:

• The full sentence is: "His friends feel that he will be suspended unless he does not report for duty immediately."
• Segment (a) is "His friends feel that".
• Segment (b) is "he will be suspended".
• Segment (c) is "unless he does not report for duty immediately".
• Segment (d) is "No error".
• We assume typical competitive exam standards for modern English usage.

Concept / Approach:
The conjunction "unless" carries a negative sense. It roughly means "if not". Because "unless" already implies a negative idea, it is usually followed by an affirmative verb form. Writing "unless he does not report" creates a double negative, which changes or confuses the intended meaning. The intended sense is that he will be suspended if he fails to report for duty. Therefore, the correct form should be "unless he reports for duty immediately" or "if he does not report for duty immediately". The other segments are grammatically acceptable.

Step-by-Step Solution:
Step 1: Understand the intended meaning: his friends think suspension will happen if he fails to report for duty soon. Step 2: Check segment (a) "His friends feel that" and see that it is a standard reporting clause introducing an opinion. Step 3: Examine segment (b) "he will be suspended", which is a correct passive future construction. Step 4: Focus on segment (c) "unless he does not report for duty immediately". Realize that "unless" already means "if not". Step 5: Notice that "does not report" adds another negative idea, leading to a confusing double negative when combined with "unless". Step 6: Recognize that the corrected clause should be "unless he reports for duty immediately". Therefore, segment (c) is the incorrect part.

Verification / Alternative check:
Rewrite the sentence using "if" to test the logic. A clear version is "His friends feel that he will be suspended if he does not report for duty immediately." This sentence uses a single negative and expresses the intended meaning. Now convert this idea back using "unless": "His friends feel that he will not be suspended unless he reports for duty immediately." This check shows that the original phrase "unless he does not report" is not consistent with the correct conditional structure. Thus our identification of segment (c) as the error is confirmed.

Why Other Options Are Wrong:
Option (a) "His friends feel that" correctly introduces a noun clause containing their belief. Option (b) "he will be suspended" is a proper future passive form and fits the meaning. Option (d) "No error" cannot be right because there is a clear structural problem in segment (c).

Common Pitfalls:
Many learners combine "unless" with negative verbs, producing phrases like "unless he does not come" or "unless you do not study". These forms are confusing and not normally accepted in standard English. Another trap is reading quickly and missing the interaction between conjunctions and negatives. To avoid such mistakes, always remember that "unless" itself means "if not", so the verb after it is usually affirmative. Training yourself to expand "unless" to "if not" in your mind is a reliable way to check if the structure is correct.

Final Answer:
The erroneous part is in option (c) "unless he does not report for duty immediately". The correct form should be "unless he reports for duty immediately". Therefore, the correct answer is "unless he does not report for duty immediately".