Sketch the following waveforms:

(a) \(v_{1}(t)=r(t+2)-r(t-2) \mathrm{V}\)

(b) \(v_{2}(t)=4+r(t+1)-2 r(t-1)+r(t-3) \mathrm{V}\)

(c) \(v_{3}(t)=\frac{d v_{1}(t)}{d t}\)

(d) \(v_{4}(t)=\frac{d^{2} v_{2}(t)}{d t^{2}}\)