 Complete the following phrase:  Christie took his examen artium in 1927, attended from 1929 to 1930 and graduated from the Technische College of Berlin in 1935. From 1936 to 1938 he worked at Trondheim Airport, Værnes as well as a lecturer at the Norwegian Institute of Technology. In 1939 he was hired in the company Norsk Aluminium, and he was on a working trip in Linköping when World War II 