 It is considered below for the transistor Q1.During State 1, Q2 base-emitter junction is reverse-biased and capacitor C1 is "unhooked" from ground.The output voltage of the switched-on transistor Q1 changes rapidly from high to low since this low-resistive output is loaded by a high impedance load (the series connected capacitor C1 and the high-resistive base resistor R2).