They trick you into thinking you are learning when you are actually just reading about the language.
Consider the PDF your map. It shows you the roads (grammar), the cities (vocabulary), and the borders (cultural taboos). But you still have to walk the walk. You still have to say “Bom dia, tudo bem?” to a confused cashier in Lisbon and get it wrong ten times before you get it right.
Don't read Chapter 1 to 10 like a novel. Use the PDF as a reference. When you learn the verb ir (to go) on Duolingo, open the PDF’s verb section. Read their explanation. Their written grammar explanations are superior to any app’s.
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