grid-template:

 "a a c" 1fr
 "b b c" 1fr
 "b b c" 1fr / 1fr 1fr 1fr;

grid-template:

 "a b c" 1fr
 "a b c" 1fr
 "a b c" 1fr / 1fr 1fr 1fr;

grid-template:

 "a b b" 1fr
 "a b b" 1fr
 "c c c" 1fr / 1fr 1fr 1fr;

grid-template:

 "a a a" 1fr
 "b b b" 1fr
 "c c c" 1fr / 1fr 1fr 1fr;