The preposition "for" is used in the sentence "Cantonments are requisite for happiness" to indicate the purpose or necessity of cantonments in relation to happiness.
It suggests that cantonments are essential or necessary for the attainment or maintenance of happiness.
The use of "had been doing" in your sentence would indicate that the action of doing the kind of work occurred before another past event.
In this case, "had been doing" implies that the kind of work you were doing happened before the doctor knew you would recover.
This construction suggests a past continuous action that was ongoing up until a specified point in the past, which is why "had been doing" is used in this context.
The continued to work in the field Even through it rained heavily.
This sentence conveys that despite the heavy rain, the individuals persisted in their work.
"Even though" is used to introduce a contrast, emphasizing the challenging weather conditions they faced while highlighting their determination to continue working in the field.
