I used to could, but I can't now.

source: 
LAGS
Entry: 
644
Example: 
I used to could, but I can't now.
Modal 1: 
used to
Modal 2: 
could
Gender: 
Male
Race/Ethnicity: 
Black
Age: 
61
Level of Education: 
4th grade
Home Community, Town, or State: 
GA (Valdosta)
Location Collected: 
GA (Valdosta)
Year: 
1971
Relation to Addressee: 
subject to fieldworker
Medium: 
Spoken
Sentence Structure: 
1.1
Status: 
Naturalistic