"If you can't come, then you must tell us" should be the correct answer. 如果...就... is an if...then... structure.
That is too literal a translation (although not wrong either). In English, it is perfectly fine to use the conditional without a 'then' to introduce the resulting clause.
It is still correct to have it in, though. Neither one is wrong. That's the point. That and the fact that, at times this site's Chinese is hyper-literal, and at times it is more free.
He did state that it's not wrong.
"If you can't come, then you have to tell us" should be accepted
Got penalised for putting "Then" in an "If...Then" sentence structure. Answer needs to be fixed to permit it.
If you (cannot/can't) (come/make it), (-/then) you (definitely have to/must) (let us know/tell us). These are all acceptable translations as in English, generally the "then" is implied and it is not colloquial to have it here.
you need to tell us is fine too
"If you can't come you must definitely tell us" is correct, but was not accepted. Please correct!
You must tell us if you cannot come
I got marked wrong for using "can't" instead of cannot
Let us know should also be accepted
If you cannot come then you must tell us
"If you cannot come then definitely tell us." should be accepted.
If you cannot come, then you have to definitely tell us.
why not: if you cannot come, then you definitely must....tell us?
I am beginning to think that this one course has too many questions. If I am not mistaken, French duolingo only have 7-10 questions per course
I hate this sentence. There are a lot of smoother translations that aren't accepted.
"if you cannot come you you definitely must tell us" This is wrong?!? Seriously guys, LEARN ENGLISH!
You should tell us if you don't come.. Should be a correct answer.. Duo is really stupid... Can you fix this ASAP. Don't know how many people are there working on it....
Do you use the paid version of Duolingo? What makes you think that you are in the position to tell Duolingo what to do "asap"?