The more interesting’ needs to be replaced with ‘the most interesting’. This is because, when making comparison between two or more things, the superlative degree is used and not the comparative degree Thus, the correct formation would be, ‘This book is the most interesting of the three’.

If some action has started in the past and is still continuing, then present perfect continuous tense should be used instead of present continuous tense. So, the phrase ‘am waiting’ needs to be replaced with ‘have been waiting’ to make the sentence contextually correct. Thus, the correct formation would be, ‘I have been waiting for three –quarters of an hour’.

If some action has started in the past and is still continuing, then present perfect continuous tense should be used instead of present continuous tense. So, the phrase ‘is working’ needs to be replaced with ‘has been working’ to make the sentence contextually correct. Thus, the correct formation would be, ‘Ramesh has been working in this factory for the past three months’.

‘Regret for’ needs to be replaced with ‘regret’ to make the sentence grammatically correct. This is because ‘regret’ is not followed by a preposition. Thus, the correct formation would be, ‘I regret using objectionable words against a man so mighty’.

‘To dispose of’ is the correct phrase to be used here. It means to get rid of something by selling or giving. Thus, the correct formation would be, ‘Raman wants to dispose of his house’.

‘Sitting on the fence’ is the correct idiom used. It is used to describe a person’s lack of decisiveness, neutrality or hesitance to choose between two sides in an argument or a competition, or inability to decide due to lack of courage. Thus, the sentence is grammatically and contextually correct. Thus, the correct formation would be, ‘Decide one way or the other; you can’t be sitting on the fence forever’.

The phrase ‘that he could not serve’ is grammatically correct. This is because other forms of verb doesn’t go with the blank and this form of verb is grammatically and contextually correct. Thus, the correct formation would be, ‘He was too conscientious in the discharge of his duties to serve that exploiter for long’.

The question tag ‘isn’t it’ needs to be replaced with ‘can’t we’. This is because the sentence and the question tag must be in the same tense and the same pronoun is to be used in the question tag. Thus, the correct formation would be, ‘we can go out whenever we choose to, can’t we?’