Questions

‘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 ‘has been thrusted’ is grammatically correct. This is because, when someone is forced to accept or deal with, this form of verb is used. Thus, the correct formation would be, ‘Heavy work has been thrust on me’.