[may could] may used to [might could] might had better [might supposed to] 
used to could
m i g h t ’ v e u s e d t o
m i g h t w o u l d a h a d o u g h t a
o u g h t a c o u l d
b e t t e r c a n
s h o u l d o u g h t a
u s e d t o c o u l d
m u s t a c o u l d a
w o u l d b e t t e r