모의고사 문법 질문이요..

city officials went to the state capital again to ask that something ③ be done about quieting the highway noise. they were put off repeatedly. at last the city officials had an idea. they planted a single row of trees in front of the apartment house. the trees made hardly any difference in the amount of, noise but they ④ did block the view of the highway. after that, there were very ⑤ few complaints from the people in the building.

3번에서 be대신 is가 쓰이면 안되는건가요,,?
something 이 that절에 주어이고, 동사가 나오는 자리이니까 is를 써야할 것 같은데
왜 be로 쓰였는지 알려주세요..^^ 4번에 did는 강조 맞나요,,?