Complete the sentence with the correct form of the verb in brackets: "The new gearbox ____ (cost) us three hundred pounds more than the garage first quoted."

Explanation

In the price sense — how much a buyer had to pay — this verb never changes, so the past simple keeps the base spelling even though the payment is over. The -ed spelling costed belongs to the separate accounting sense of working out a budget in advance, as when a project is costed at two million, and it is not available for what an item charged a customer.