This verb too can operate either like can and should or like an ordinary verb, but with certain reservations.
Purists dislike the question forms ? Did/Didn’t you use to wear glasses?, though it is very common, especially in American English. The alternatives, Used you to wear glasses?, Usedn’t you to wear glasses?, and Used you not to wear glasses?, are all rather formal – and the last is also ambiguous.
Similarly, some purists regard as non-standard the negative form ? I didn’t use to like cabbage. But I usedn’t/used not to like cabbage strikes others as old-fashioned. The form I never used to . . . is acceptable in cases where the action could be repeated: I never used to eat cabbage. But it is less acceptable to purists when referring to a past state: ? I never used to like her.
One solution is to avoid the structure altogether: Didn’t you wear glasses at one time? I didn’t like cabbage, and never ate it.
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