Error spotting (exam direction): Identify the erroneous part (A/B/C) — choose D if there is no error — 'He has not been attending / English classes / since one month / No error.'

Given sentence parts (A–D)
A. He has not been attendingB. English classesC. since one monthD. No error.

Concept/Approach (since vs. for)
Use 'since' with a point in time ('since Monday/2019/June') and 'for' with a duration ('for one month').

Step-by-Step correction
1) Identify duration phrase: 'one month' is a period, not a starting point.2) Replace: 'since one month' → 'for one month'.3) Correct sentence: 'He has not been attending English classes for one month.'

Verification/Alternative
If a starting point were given (e.g., 'since 1st August'), 'since' would be correct.

Common pitfalls
Overusing 'since' in place of 'for' with durations.

Final Answer
C — 'since one month' should be 'for one month'.