1. 다음 글의 밑줄 친 부분 중 어법상 잘못 쓰인 것은?

① The police are putting cameras at street intersections. ② The cameras take pictures of cars running red lights. One camera shows 80 to 100 of them a day. ③ Run red lights is a big problem. It Causes about 1,000 accidents a year. ④ The cameras seem to be working. ⑤ There are 40% fewer red light runners at the intersections with cameras.