There is a group 2 indicator (only) and a group 4 indicator (cannot) in that sentence. So you can use either one, but generally it's easier to use group 4 indicators as negations and use the other one as the logical indicator.
Can I ask why- if we can (generally) predict the outcome of our tests, based off of where we were PTing before hand, how many questions we guessed on, and how quickly we ran out of time?
I am not an expert like others here so i could be wrong. Have you analysed in which type of questions this tends to happen? Is it one type or more than one?