Complex sentence: The pieces of the Soma cube consist of all possible non-regular (i.e. excluding rectangles) combinations of four or less unit cubes (excluding the 2x2x1 square and a 4x1x1 line), and addition of a right-angle piece of only three blocks.
Split into simpler sentences: The pieces of the Soma cube consist of all possible non-regular (i.e. excluding rectangles) combinations of four or less unit cubes. Note the lack of a 2x2x1 square and a 4x1x1 line, and addition of a right-angle piece of only three blocks.