Complex sentence: The Philippine Air Force first received the Sabres in the form of F-86Fs in 1957, replacing the North American P-51 Mustang as the Philippine Air Force's primary interceptor.
Split into simpler sentences: The Philippine Air Force first received the Sabres in the form of F-86Fs in 1957. Replacing the North American P-51 Mustang as the Philippine Air Force's primary interceptor.