Formulate a musical piece by utilizing the specified motif and alphabet-based structure.
X:1
L:1/8
Q:1/4=140
M:4/4
K:Bb
['B2 FB DBFB', 'BBdB fBdB']  
X:1
L:1/8
Q:1/4=140
M:4/4
K:Bb
 d | B2 FB DBFB | B2 (d/c/B) Accd | B2 FB DBFB | (A/B/c) c>e dB B :: d | BBdB fBdB | BBdB Accd | 
 BBdB fBdB | A/B/c ce dBBd | BBdB fBdB | BBdB Accd | dbca BgAf | fgbf dB B :|  