The brake builds up pressure gradually, because it is found that the deceleration rate is abnormal, depress the pedal fully and ask the co-pilot to assist.
The brakes gradually build up pressure because the deceleration rate is found to be abnormal, press the pedal at full force and ask the co-pilot to assist in pedaling.
The brake pressure is gradually built up, because it is found that the deceleration rate is abnormal. Step on the pedal with all your strength and ask the co driver to help step on the pedal.