For "Sie ist nicht zu ersetzen" the answer I submitted was "She is not to be replaced" and it was marked wrong. Did DuoLingo misjudge or is the meaning wrong?
The suggested correct solution is "She cannot be replaced" -- but where is a word that means "CANNOT" in the sentence? Wouldn't that be something like "Sie kann nicht zu ersetzen werden" ??? (Excuse any errors in that suggestion, I haven't learned the passive voice yet and I am a beginner in general)
I suppose the "nicht zu" would be the equivalent of "cannot".
The sentence is ambiguous between "She is not to be replaced" (i.e. an admonition: don't replace her! that's not allowed) and "She cannot be replaced" (i.e. a statement: it's not even possible to replace here even if you did try).
You could say the more literal "Sie kann nicht ersetzt werden" for "She cannot be replaced".
Compare also "Nicht zu glauben!" for "Unbelievable!" -- this also shows the "it cannot be believed" meaning of "nicht zu".
I wish they would put notes like this in the beginning of the lesson.
I agree, these are the kinds of tidbits that would make it a lot easier to learn this language. Heck, even a list of the vocabulary being introduced would be useful.
So, 'nicht zu' is a bit idiomatic, and it looks like it can often be translated as English "un_able". That's quite helpful!
Isn't the werden in your suggestions superfluous? I'd translate "She cannot be replaced" as "Sie kann nicht ersetzen". Is that wrong? How come?
Edit: I dunno why I made this comment. What I suggest obviously is not passive... Thank you for the correction clarification!
I find it very difficult to imagine how I am going to be able to distinguish between the times ersetzen means "to replace something" versus "to be replaced by something." Or am I just not thinking through how context will help with that?
It's not that ersetzen sometimes means "replace" and sometimes "to be replaced".
It's that a German construction with (nicht) zu [active verb] is often best translated into English as "can(not)/(should) not be [passive verb]ed".
Similarly with dieser Code ist nicht zu knacken "this code cannot be broken", where knacken does not mean "to be broken" but "to break" -- it's the (nicht) zu which shifts the translation.
Or for a positive sentence: in diesem Bereich sind Helme zu tragen "helmets are to be worn in this area" -- tragen means "to wear" and not "to be worn", but Helme sind zu tragen means "helmets are to be worn" and not "helmets are to wear".
Können wir also einen andere Beispiel zu einschließen: "Er ist nicht zu fassen." Ist das recht? Is it an indiomatic expression for "He is not to be believed." which is something I've heard down South in the U.S., and I suspect it's also used elsewhere. But would this also mean that He cannot be caught?
She is not to be replaced is accepted as of September, 2016. Duolingo suggests She cannot be replaced. as the best translation.
"She is not to be replaced" is different from "She cannot be replaced". The former suggests a lack of permission. The latter demonstrates dependance.