First, you don’t mean active/passive tense, per se.
Active tense: The lecture bored me.
Passive: I was bored by the lecture.
You’re talking about active and passive voice participle adjectives.
When you describe how the subject feels, use past participle:
Gus was bored.
When you are describing object that causes the reaction, use the present participle form.
Gus’s topic is boring.
Your girlfriend needs drilling. (No jokes, please! )
Get some exercises from the internet, or grammar books, or write some up yourself that may have some meaning to you both.
Have her do them. Taiwanese learn well this way. Rote learning is ingrained in their learning styles from a young age. Also, Taiwanese are freaks when it comes to grammar. So explain the grammar clearly.
Ask her: Did the object do the action itself, or was the action done to it by someone else?
Correct her every time she makes a mistake by slapping her hand with a ruler. Eventually, she’ll get it.
langara.bc.ca/writingcentre/ … ssive.html