Frequent error with "used to" in lessons using costumar
Duolingo repeatedly marks my sentences wrong when I use "used to" as opposed to "use to" for costumar. This is wrong. The correct form in English is "used to". It's a bit frustrating to have to type faulty English to get something right. http://www.grammar.cl/rules/used-to-use-to.htm
I reported this a couple of weeks ago and got a response from the duolingo team saying they got my report. I'm sure they are working on it but it wouldn't hurt to let them know others are having an issue with that lesson as well.
Report it! Some people do these lessons to learn English, so it's worth getting the English grammar right. You can use the Report button on the bottom of the Lesson pages whenever you see a mistake in English or Portuguese.
Although--and I'm sure you already know this--there are certain cases where "use to" is correct. http://oald8.oxfordlearnersdictionaries.com/dictionary/used-to
Well....the website talks about "past". What about "present"?
The tense of "use" follows the tense of "costumar".
Eu costumo acordar cedo - I use to wake up early (this is present tense, not past)
Eu estou acostumado a comer cedo - I'm used to eat early
Eu costumava correr - I used to run (this is past)
Actually, the core meaning of "costumar fazer algo" is "to be in the habit of doing something" (Larousse Portuguese Dictionary, 2008, page 99). And when we want to say "estar acostumado a fazer algo" we employ "to be used to doing something" (with a gerund).
So the English translations of your first two examples are as follows:
Eu costumo acordar cedo. "I usually wake up early." Or "I'm in the habit of waking up early" (As iamjeff77 pointed out in his original post, "use to" is incorrect.)
Eu estou acostumado a comer cedo. "I'm used to eating early." (You need to use the gerund here.)
Your third example (Eu costumava correr - I used to run) is correct.