In the following sentence, identify the part that contains a grammatical or usage error: "He recommended / my case / with the supervisor."

Introduction / Context:
This error-detection question tests your understanding of correct verb-preposition combinations (collocations) in English. The verb "recommend" is often used in formal communication, and using the wrong preposition can make a sentence sound unnatural or incorrect. Here the sentence is about someone recommending a case to a supervisor.

Given Data / Assumptions:
- The sentence is broken into: (A) "He recommended" (B) "my case" (C) "with the supervisor".
- We must choose the part that contains the mistake.
- The intended meaning is that he spoke favourably about my case to the supervisor or advised my case to the supervisor's attention.

Concept / Approach:
In standard English, we use "recommend something to someone" or "recommend someone to someone". The common preposition with "recommend" in this pattern is "to", not "with". For example, "He recommended my case to the supervisor" or "She recommended me to the manager." The preposition "with" in this context is incorrect.

Step-by-Step Solution:
Step 1: Read the full sentence: "He recommended my case with the supervisor."
Step 2: Focus on how "recommend" is typically used when you mention both the thing recommended and the person receiving the recommendation.
Step 3: Recall the correct pattern: "recommend + object + to + person", for example, "He recommended my case to the supervisor."
Step 4: Identify that the error lies in part C, "with the supervisor", which should be "to the supervisor".

Verification / Alternative check:
Consider similar sentences: "He discussed my case with the supervisor" is correct because the verb "discuss" regularly takes "with". However, "He recommended my case with the supervisor" sounds unnatural and is not idiomatic. Changing it to "He recommended my case to the supervisor" restores correct collocation and natural English usage.

Why Other Options Are Wrong:
- Part A, "He recommended", correctly introduces the verb and the subject.

- Part B, "my case", correctly gives the object of the recommendation.
- Part D, "No Error", is wrong because we have identified a clear preposition error in part C.

Common Pitfalls:
Because many verbs use "with" to indicate a person you talk to or interact with, students sometimes apply "with" incorrectly after "recommend". To avoid this, memorise a few common combinations such as "recommend something to someone", "introduce someone to someone", and "refer someone to someone". Recognising these patterns will help you automatically spot errors in preposition usage during exams.

Final Answer:
The error is in part C; it should be "to the supervisor" instead of "with the supervisor".