Complex sentence: The 737 MAX is the fourth generation of the 737 family, with the primary change being the use of the larger and more efficient CFM International LEAP-1B engines and modifications to the airframe.
Split into simpler sentences: The 737 MAX is the fourth generation of the 737 family. The primary change is the use of the larger and more efficient CFM International LEAP-1B engines and modifications to the airframe.