"She always knew."
Translation:Lei ha sempre saputo.
I think I finally understand DL's purpose in putting the "She always knew" statement in the Past Imperfect lesson. If I see the word "sempre," and I'm in the Past Imperfect section, I'm going to plunk down a Past Imperfect verb. But as Cab Calloway would sing, "It ain't necessarily so." Way to keep us on our toes, Duo!
It seems to me that the problem here is that an English simple past can be translated as either a perfect or imperfect tense. Presumably what the DL people had in mind is "she always knew" as a way of saying "she has always known" so "ha saputo", but "she always knew" could mean "she always used to know" (when we were lying etc.) and this would be translated as "sapeva". DL should allow both.
"She always knew the answer"=sapeva sempre la risposta. "She always knew how to do"= sempre sapeva come fare (a bit literary, but correct if you want to emphasise that she knew "always"). But "lo ha sempre saputo"= she had always known. I don't agree with duolingo translation.
Conoscere is for when you are acquainted with someone or something. I know her. I know New York City. I know that book. Sapere is for when you know about something. I know how to swim. I know that you are sorry. I know that what you say is true. So if you say, "I know!", you need sapere. If you say, "I know her", you need conoscere. Does that make sense? In this one there is no direct object - so sapere is the only choice.
Lei sapeva sempre = Why is this not acceptable? Can both versions surely mean, She always knew: Lei sapeva sempre, e Lei ha sempre saputo. Especially as this sentence was in the Past Imperfect Skills section, the sentence Lei sapeva sempre should not be an invalid answer.