Questions

enum assigns numbers starting from 0, if not explicitly defined.

The modal ‘Could’ is used to express possibility. It is simply used to state one or more things that are possible or were possible in the past. In this statement, ‘to have achieved’ needs to be replaced with ‘for achieving’ to make the sentence correct. Thus, the correct sentence would be, ‘When I finished writing the letter, I could not help admiring myself for achieving the impossible’.

Were’ needs to be replaced with ‘was’ to make the sentence grammatically correct. This is because,‘If the subjects are joined by as well as, with, along with, together with, and not, in addition to, but, besides, except, rather than, accompanied by, like, unlike, no less than, nothing but, led by, headed by, guided by, controlled by, governed by,etc..Then the verb will agree with the first subject’ Thus, the correct sentence would be, ‘Coleridge as well as Wordsworth was of the opinion that the opposite of poetry os not prose but science’.