Zheng took out the air cannon as soon as he was hit and pressed the trigger at once. He was still being pushed by the force and was already five meters away from the roof.
Zheng could feel the force weakening then he began to fall. In just a moment, he had fallen from the roof to previous floor. The cannon was still charging.
Zheng was falling faster and faster. He held onto both the air cannon and the progressive knife. Then the cannon sent a big recoil effect from his left hand and pushed him toward the glass wall. Zheng stabbed the knife into the glass without activating the knife then used it as a support to jump up using the movement technique.