He used coloured chalk
whenever it was available and whenever it helped.
He used coloured chalk
|
whenever it was available
|
and whenever it helped
|
α
|
x β
|
|
1
|
+ 2
|
|
He used coloured chalk
sporadically and whenever it helped.
He used coloured chalk sporadically
|
and he used coloured
chalk
|
whenever it helped
|
1
|
2
|
|
| α |
x β
|
|
