Difficulty: Easy
Correct Answer: by
Explanation:
Introduction / Context:
This question tests the correct use of prepositions in common English expressions. The phrase make a fortune is often followed by a preposition that introduces the method or activity through which the money was earned. Identifying the most natural and grammatically correct preposition is essential for sounding fluent and accurate in English.
Given Data / Assumptions:
Concept / Approach:
In English, when we indicate the means or method by which something is done, the preposition by is frequently used. For example, make money by teaching, become famous by writing novels, or improve fitness by exercising daily. The sentence here describes the way Naresh earned his fortune. Therefore, the correct preposition is by, because it introduces the activity that served as the method of earning.
Step-by-Step Solution:
Step 1: Focus on the expression made a fortune, which means earned a very large amount of money.Step 2: Identify that the phrase buying and selling used cars tells us how he earned this fortune.Step 3: Recall the common pattern make a fortune by doing something.Step 4: Insert by into the sentence: Naresh made a fortune by buying and selling used cars. This reads smoothly and accurately.Step 5: Check at, which is used for locations or specific occasions, such as at school or at the party, and does not fit here.Step 6: Check in and on, which are used for spaces, surfaces, or certain fixed phrases, not for introducing a method of making money.
Verification / Alternative check:
Try forming similar sentences. A businesswoman made a fortune by investing in technology, and He made a fortune by exporting spices are entirely natural. Replacing by with at, in, or on would make the sentences awkward and ungrammatical. For example, made a fortune at buying and selling used cars does not align with typical English collocations. This confirms that by is the only preposition that correctly introduces the method of earning in this context.
Why Other Options Are Wrong:
AT is commonly combined with places or times (at home, at noon) and occasionally with skills (good at chess), but not with earning money through an activity in this structure. IN is used with locations and fields (in the city, in medicine) and would require rephrasing such as in the business of buying and selling cars, which is not the given structure. ON is used with surfaces and some idioms (on the table, on purpose) and does not fit directly before a gerund phrase describing a method.
Common Pitfalls:
Many learners choose in because they think of being in a business, but the sentence does not say in the business of. Others may rely on literal translation from another language and choose at or on. A reliable strategy is to recall fixed patterns in English, such as by doing something for methods, and use those to guide the choice of preposition.
Final Answer:
The correct preposition to complete the sentence is by, giving Naresh made a fortune by buying and selling used cars.
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