But you used to couldn't.

source: 
LAGS
Entry: 
616
Example: 
But you used to couldn't.
Modal 1: 
used to
Modal 2: 
couldn't
Gender: 
Female
Race/Ethnicity: 
Black
Age: 
72
Level of Education: 
6th-7th grade
Home Community, Town, or State: 
LA (Sterlington)
Location Collected: 
LA (Sterlington)
Year: 
1975
Relation to Addressee: 
subject to fieldworker
Medium: 
Spoken
Sentence Structure: 
1.0
Status: 
Naturalistic