/clever/ has two meanings in English, which in Italian are with different words: a) bravo (positive meaning) b) furbo (negative meaning) Penso che tu sia {bravo, furbo} (depending upon the context) Note that /pensare/ usually needs the conjunctive mode, but also indicative mode could do the job: Penso che tu sei {bravo, furbo} Or, completely changing the form, but not the meaning: Ti reputo {bravo, furbo}

"I think that" in italian is "io penso che" "I know that" is "io so che" that in this case is translated as "che"

pronome relativo: (as subject, object) che, il quale, la quale, i quali, le quali; (with preposition) il quale, la quale, i quali, le quali, cui; the woman that won----> la donna che ha vinto; the book that I bought --->il libro che ho comprato; the house that they live in---> la casa in cui vivono; the day that she arrived---> il giorno in cui arrivò