Construct a musical composition utilizing the provided motif and conforming to the specified structure.
X:1
L:1/8
M:2/4
K:A
["b3/2 b/ b2 e' b a f"]  
X:1
L:1/8
M:2/4
K:A
 b3/2 b/ b2 | e' b a f | ^d e f =d | B4 | b3/2 b/ b2 | e' b a f | ^d e f2 | e4 |]  