Read the following sentence and identify the part that contains an error, or select "No error" if the sentence is correct: "If a thing is worth doing at all it is worth done well."

Introduction / Context:
This question tests your understanding of the correct structure of the common proverb "If a thing is worth doing at all, it is worth doing well." The given sentence almost matches the proverb, but there is a grammatical error in the final part. Your job is to identify which segment contains the mistake.

Given Data / Assumptions:

• Full sentence: "If a thing is worth doing at all it is worth done well."
• Parts: (a) If a thing, (b) is worth doing at all, (c) it is worth done well., (d) No error.
• The intended meaning: if an activity is worth doing, it should be done properly.

Concept / Approach:
The phrase "is worth doing" correctly uses the -ing form of the verb after "worth". The second part of the proverb must mirror this structure: "is worth doing well". However, the sentence uses "worth done well", which is incorrect. "Done" is a past participle and does not fit grammatically after "worth" in this construction. The error is therefore in part (c).

Step-by-Step Solution:
Step 1: Examine part (a): "If a thing". This is a standard beginning to a conditional proverb.Step 2: Examine part (b): "is worth doing at all". This is correctly formed; "worth" is followed by a gerund ("doing").Step 3: Examine part (c): "it is worth done well." Here, "done" is a past participle and is not used correctly after "worth".Step 4: The correct phrase should be "it is worth doing well", matching the gerund pattern used earlier.Step 5: Thus, part (c) is the erroneous segment.

Verification / Alternative check:
Rewrite the sentence using the standard proverb: "If a thing is worth doing at all, it is worth doing well." This version is grammatically correct and widely recognised. Read the original: "If a thing is worth doing at all it is worth done well." The last part clearly sounds wrong, because "worth done" does not form a natural English phrase. This confirms that part (c) is where the correction is needed.

Why Other Options Are Wrong:
Part (a) "If a thing" is a correct conditional opener and needs no change. Part (b) "is worth doing at all" exactly matches standard usage. Option (d) "No error" is not correct because we have identified an actual grammatical problem in part (c).

Common Pitfalls:
Because this sentence closely resembles a well-known proverb, some students read quickly and assume the entire line is correct, choosing "No error". Others may overthink the phrase "worth doing at all" even though it is perfectly standard. The key is to carefully examine verb forms after "worth" and ensure that they are in the -ing form (gerunds) when expressing activities. Remember: "worth doing", not "worth done".

Final Answer:
The error is in part "it is worth done well."; it should be "it is worth doing well."