Examples from Minor scale:

 {
% ##f := false
\override Score.TimeSignature #'stencil = ##f
\relative c' { 
  % force bar line after 7th note
  \clef treble \time 7/4
  c4^\markup { C natural minor scale } d es f g aes bes c2
  }

}
 {
\override Score.TimeSignature #'stencil = ##f
\relative c' { 
  \clef treble \time 7/4
  c4^\markup { C major scale } d e f g

\override NoteHead.color = #red a \override NoteHead.color = #black b c2 \bar "||"
  \time 9/4
  \override NoteHead.color = #red a,4^\markup { A natural minor scale } \override NoteHead.color = #black b c d e f g a2 }

}
 {
\override Score.TimeSignature #'stencil = ##f
    \relative c' {
% Another trick for hiding bar lines
        \clef treble \time 7/1 \hide Staff.TimeSignature
        <a c e>1_\markup i
        <b d f>_\markup ii°
        <c e gis>_\markup III+
        <d f a>_\markup iv
        <e gis! b>_\markup V
        <f a c>_\markup VI
        <gis! b d>_\markup vii°
    }

}

Examples from Cadence (using Image frames):


    {
      \new PianoStaff <<
        \new Staff <<
            \new Voice \relative c'' {
                \stemUp \clef treble \key c \major \time 4/4
                d2 b c1
                }
            \new Voice \relative c' {
                \stemDown
                f2 d e1
                }
            >>
        \new Staff <<
            \new Voice \relative c' {
                \stemUp \clef bass \key c \major \time 4/4
                a2 g g1
                }
            \new Voice \relative c {
                \stemDown
                d2 g, c1 \bar "||"
                }
            >>
    >> }
Perfect authentic cadence (V–I with roots in the bass parts and tonic in the highest voice of the final chord): ii–V–I progression in C major, four-part harmony (Benward & Saker 2003, p. 90).

    {
      \override Score.SpacingSpanner.strict-note-spacing = ##t
  \set Score.proportionalNotationDuration = #(ly:make-moment 1/8)
      \new PianoStaff <<
        \new Staff <<
            \relative c'' {
                \clef treble \key c \minor \time 4/4
                c4-. d-.(\f\trill \grace {c16 d} es4-.) <b d b'>-. <c es c'>
                }
            >>
        \new Staff <<
            \relative c' {
                \clef bass \key c \minor \time 4/4
                c4-. <g b>-. <c, c'>-. <g g'>-. <c, c'>
                }
            >>
    >> }
A perfect authentic cadence in Beethoven's Piano Sonata No. 8, mvmt. III, mm. 16–17.

In a perfect authentic cadence (PAC), the chords are in root position...


   \new PianoStaff <<
      \new Staff <<
         \new Voice \relative c'' {
             \stemUp \clef treble \key c \major \time 4/4
             b1 c 
             }
         \new Voice \relative c'' {
             \stemDown
              g1 g
              }
            >>
     \new Staff <<
         \new Voice \relative c' {
             \stemUp \clef bass \key c \major \time 4/4
             d1 e
             }
         \new Voice \relative c' {
             \stemDown
             g1 c, \bar "||"
             }
         >>
    >>

Blah


   \new PianoStaff <<
      \new Staff <<
         \new Voice \relative c'' {
             \stemUp \clef treble \key c \major \time 4/4
             d1 e 
             }
         \new Voice \relative c'' {
             \stemDown
              g1 g
              }
            >>
     \new Staff <<
         \new Voice \relative c' {
             \stemUp \clef bass \key c \major \time 4/4
             b1 c
             }
         \new Voice \relative c' {
             \stemDown
             g1 c, \bar "||"
             }
         >>
    >>

blah


   \new PianoStaff <<
      \new Staff <<
         \new Voice \relative c'' {
             \stemUp \clef treble \key c \major \time 4/4
             b1 c1
             }
         \new Voice \relative c'' {
             \stemDown
              g1 g1
              }
            >>
     \new Staff <<
         \new Voice \relative c' {
             \stemUp \clef bass \key c \major \time 4/4
             d1 c1
             }
         \new Voice \relative c' {
             \stemDown
             g2 f e1 \bar "||"
             }
         >>
    >>

   \new PianoStaff <<
      \new Staff <<
         \new Voice \relative c'' {
             \stemUp \clef treble \key c \major \time 4/4
             c1 b 
             }
         \new Voice \relative c'' {
             \stemDown
              g1 g
              }
            >>
     \new Staff <<
         \new Voice \relative c' {
             \stemUp \clef bass \key c \major \time 4/4
             e1 d
             }
         \new Voice \relative c {
             \stemDown
             c1 g' \bar "||"
             }
         >>
    >>

    {
      \new PianoStaff <<
        \new Staff <<
            \new Voice \relative c'' {
                \stemUp \clef treble \key e \minor \time 4/4
                \partial4 a4 b8 a g4 fis e8 fis g4 a b \fermata
                }
            \new Voice \relative c' {
                \stemDown
                \partial4 d4 d8 dis e4 dis e8 dis e[ g] fis e dis4
                }
           \addlyrics { Lord, with _ Thy grace my _ soul _ re - fresh! }
            >>
        \new Staff <<
            \new Voice \relative c' {
                \stemUp \clef bass \key e \minor \time 4/4
                \partial4 a g8 a b4 b b8 a b4 c fis,
                }
            \new Voice \relative c {
                \stemDown
                \partial4 fis4 g8 fis e4 b'8[ a] g fis e d c4 b_\fermata
                }
            >>
    >> }
A Phrygian half cadence in Bach's four-part...

    {
      \new PianoStaff <<
        \new Staff <<
            \new Voice \relative c'' {
                \stemUp \clef treble \key e \minor \time 4/4
                \partial4 a4 b8 a g4 fis e8 fis g4 a b \fermata
                }
            \new Voice \relative c' {
                \stemDown
                \partial4 d4 d8 dis e4 dis e8 dis e[ g] fis e dis4
                }
           \addlyrics { Lord, with _ Thy grace my _ soul _ re - fresh! }
            >>
        \new Staff <<
            \new Voice \relative c' {
                \stemUp \clef bass \key e \minor \time 4/4
                \partial4 a g8 a b4 b b8 a b4 c fis,
                }
            \new Voice \relative c {
                \stemDown
                \partial4 fis4 g8 fis e4 b'8[ a] g fis e d c4 b_\fermata
                }
            >>
    >> }
A Phrygian half cadence in Bach's four-part...