You need to learn some sets of set expressions, so-called 'functional phrases', like 'How are you?', 'I didn't mean it' and so on. They include meeting people, asking for help, apologising, expressing opinions, saying 'no' politely and so on. Other than that, it doesn't make sense to learn the whole sentences.
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as you can see here , they can also be topical — bleeds into ~ form language islands by drilling topic-specific sentences of your own creation, then?
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see also #pragmatic-markers