Identify the part of the following sentence which contains an error.
Since four (a) years he (b) has been (c) teaching here. (d)

Correct option is A

Option (a) contains an error.
Detailed Explanation (English):
• “Since” is used with a point of time (since 2018, since Monday, since morning).
• “Four years” is a period of time, so we use for, not since.
• Therefore, “Since four years” is incorrect; it should be “For four years”.
Correct sentence: For four years he has been teaching here.
(Also acceptable: He has been teaching here for four years.)
Grammatical Rule Used (English):
• Since + point of time (starting time)
• For + period/duration of time
• Present Perfect / Present Perfect Continuous is commonly used with since/for for duration.
Grammatical Rule Used (Hindi):
• “Since” का प्रयोग समय के बिंदु के लिए होता है (जैसे since 2020, since Monday)।
• “For” का प्रयोग समय की अवधि के लिए होता है (जैसे for four years, for two hours)।
• “Since four years” गलत है क्योंकि “four years” अवधि है, बिंदु नहीं।
Example:
• He has lived here since 2019.
• He has lived here for five years.