Complete the sentence with the correct form of the verb in brackets: "Half the field had ____ (burn) before the first fire engine arrived."

Explanation

The past perfect had needs a participle, and this verb has a pair of them that differ only in regional preference. The -t spelling dominates in British writing and survives everywhere as an adjective, as in burnt toast; the -ed spelling is the usual form in American English and is frequent in Britain too. Neither one is a mistake, so either spelling completes the sentence.