Understanding the Grammatical Error

The original sentence is "He is no clever to make sound business decisions." The underlined phrase is "no clever to make". This construction is grammatically incorrect in English.

The error lies in the use of "no clever to". When we want to express that someone lacks a certain quality to the degree necessary for a particular action, we typically use the structure "not + adjective/adverb + enough + to + infinitive".

Analyzing the Options

Let's look at the provided options and see which one correctly addresses the grammatical error and improves the sentence.

• Option 1: not clever enough to make
• Option 2: not enough clever to make
• Option 3: not clever to be making
• Option 4: No improvement required

Detailed Analysis of Each Option:

• Option 1: not clever enough to make

  This option uses the structure "not + adjective (clever) + enough + to + infinitive (make)". This is the correct grammatical structure for expressing a lack of sufficient quality to perform an action. The sentence becomes "He is not clever enough to make sound business decisions," which is grammatically sound and conveys the intended meaning.

• Option 2: not enough clever to make

  This option places "enough" before the adjective "clever". In standard English, "enough" follows the adjective it modifies when used with the "enough to" construction. Therefore, "enough clever" is incorrect. The correct order is "clever enough".

• Option 3: not clever to be making

  This option uses the structure "not + adjective (clever) + to + continuous infinitive (be making)". While "to be making" is grammatically valid as a continuous infinitive, its use here slightly alters the nuance. The original sentence implies a general lack of the quality (cleverness) needed for the action (making decisions). The simple infinitive "to make" is more appropriate for describing the general ability or lack thereof. More importantly, the core issue with "no clever to" isn't fully fixed by just changing the infinitive form; the "enough" part is missing to express the degree of cleverness required.

• Option 4: No improvement required

  As discussed earlier, the original sentence "He is no clever to make sound business decisions" contains a grammatical error in the phrase "no clever to". Therefore, improvement is required.

Conclusion on the Best Option

Based on the grammatical rules for expressing insufficient degree using adjectives and infinitives, option 1, "not clever enough to make", is the only grammatically correct way to improve the underlined segment and make the sentence meaningful and proper.

The correct sentence structure is: Subject + linking verb (is) + not + adjective + enough + to + base verb + rest of sentence.

Revision Table: Key Grammar Points

Additional Information: 'Enough' Placement

The word 'enough' has different placements depending on whether it modifies an adjective, an adverb, or a noun.

• When 'enough' modifies an adjective or an adverb, it comes after the adjective or adverb.
• Example with adjective: You are kind enough to help.
• Example with adverb: She speaks loudly enough to be heard.
• When 'enough' modifies a noun, it usually comes before the noun.
• Example with noun: We have enough time.

In our sentence, 'enough' modifies the adjective 'clever', so it must come after 'clever', as correctly shown in the improved option: "not clever enough to make".