Raman is confident of speaking English _______ six months as he has been…

Correct words: within, for

Explanation:

• within — indicates a time limit or deadline (by or before a stated time). It fits here because it shows when he expects to be able to speak English (by six months).

• for — indicates duration. 'For the last three weeks' correctly shows how long he has been practising up to now.

• Why the other choices are not ideal:

  • 'during' is used for happening within a period but does not express achieving something by a deadline as clearly as 'within'.

  • 'since' requires a specific start point (for example, 'since March' or 'since last Monday'); 'since the last three weeks' is unidiomatic.

  • 'in the last three weeks' can sometimes describe activities that occurred at times inside that period, but 'for the last three weeks' better emphasises continuous practice.

Complete sentence: Raman is confident of speaking English within six months as he has been practising regularly for the last three weeks.