一、单项填空 1.is this school ______ we are going to visit next week? a. that b. to which c. the one d. there 2. ---- did mr.sung buy any reading materials for you when he was in the us? ---- he was always meaning to, but he never _______. a. do b. done c. does d. did 3.he paid the boy $10 for washing ten windows, most of ____ hadn’t been cleaned for ten years. a. that b. which c. those d. them 4._______ is often the case, we have worked out the production plan.