Помогите  пожалуйста переведите  и выберите  правильный  ответ  и почему  его  мы выбрали имено этот  вариант 

    Вот задание  Open   The brackets and  complete the sentences  using past simple ,  past continuous  or past  perfect.   1. Our teacher explained  to us that Americans ( wrote/ had written) their Constitution 200 years  before  and it ( worked/ was working )  still.   2. I was  not sure  that  in the  USA the  judges  ( worked /  had worked) in the Supreme  Court  as long  as they ( lived / were living) . 3.  When my  brother ( came / was coming ), I just  ( finished / had finished  ) reading the documents. 4 . William  ( sighed / had sighed ) all the papers  by 6 o'clock.  5.  The  conference  (  began / had begun).  Before James  ( arrived/ had arrived ).