Construct a musical work following the provided guidelines and thematic elements.
X:1
L:1/8
Q:1/4=120
M:4/4
K:G
['B2 d>B G2 B>G ABcA GFED', 'fdBa gfed dcBA'  
X:1
L:1/8
Q:1/4=120
M:4/4
K:G
 B2 d>B G2 B>G | ABcA GFED | GFGA GFGA | BdcB B2 ^A2 | B2 d>B G2 B>G | ABcA GFED | edef gdec | 
 B3 A"_NB" G4 ::[K:D]"^Key sig G in ms""_NB" a4 fdBa | gfed dcBA | ddcd fede | 
"_bar missing in ms? guessed here" fagf f2 e2 |"_NB" a4 fdBa | gfed dcBA | FAdf ecAc | d3 d d4 :|  