In one of the questions I am trying to resolve, I am given the Vbe waveform and I am told to draw "waveforms related to Q1". I am guessing that means the emitter voltage waveform - right?

The Vbe waveform:

This is the buck converter circuit:

The Vbe waveform seems very vague to me. I cant understand what that horizontal plateau in the middle of the positive part signifies?