One of the constructions that English learners learn very early is “used to do”. We can say, for example
- I used to go there.
- I used to play the guitar.
So it would seem logical that “use to do” (in the present tense) should correspond to the English verb “do”, but it doesn’t. The phrase “use to do” does not exist in English. If we want to express that we “do” something, we use expressions like “regularly”, “sometimes”, etc. in conjunction with the present tense:
- I used to play the guitar. (correct expression of the past)
- I regularly play the guitar. (correct present tense)
- I use to play the guitar. (incorrect)
It doesn’t help students that native English speakers sometimes write “use to do”. However, this is a common grammatical error – since the “d” in “used” is often merged with the following “t” in pronunciation (i.e. “used to do” is commonly pronounced “juztudů”), some native speakers misspell the phrase as “use to do”. When a native speaker writes “I use to do”, he or she actually means “I used to do”.