QUESTION 15. Read the passage and fill a suitable word in each gap: TRAFFIC LIGHTS Modern traffic lights are an American invention. Red-green systems were installed in Cleveland (1)   ________  1914. Three-colour signals were (2)  _________  in New York in 1918. They used (3)________ be operated by hand from a tower in the middle of the street. The first lights of this type appeared in London, on the junction between St. James Street (4)____________ Piccadilly, in 1925. Automatic signals were installed a year later. In the past, traffic lights used to (5)_________ very special. In New York, some lights used to (6)____________ a statue on top. In Los Angeles, the (7)______________ did not just change silently, but would ring bells :c .vake the sleeping motorists of the 1930s. These are gone and have been replaced by modern systems that (8)_____________seen everywhere now.