Okay, so when we talk or write, we use words to say what we mean. Sometimes, we use a special kind of word called a verb to show what we are doing or what is happening.
But sometimes, these verbs can be broken, meaning they don't work the way they are supposed to. We call these verbs "defective" because they have a flaw, like a toy that doesn't work anymore.
For example, let's say we have the verb "to can." This means putting food in a can to keep it fresh. But sometimes, we might want to use it to say something like "I cans," which doesn't sound right because the verb is broken. Instead, we need to use a different form of the verb, like "I can" or "I could."
So, a defective verb is like a toy that doesn't work anymore. We have to be careful to use the right form of the verb so that our sentences make sense.