Complex sentence: Canard aircraft cannot use high-lift flaps effectively on the main wing, due to the far aft position of the wing trailing edge, which induces a strong negative pitching moment that a small forward wing is unable to trim in pitch.
Split into simpler sentences: Canard aircraft cannot use high-lift flaps effectively on the main wing, due to the far aft position of the wing trailing edge. Flaps induce a strong negative pitching moment that a small forward wing is unable to trim in pitch.