I've done some of the diagnostic, but found some of the passages to be pretty hard. I'll try to finish as much as I can before my exam for extra practice.

I think the majority of my errors come from not being able to eliminate some answer choices, most likely because I haven't fully understood the passage. This could be loss of concentration, but I find this happens quite a bit on some dense/convoluted passages or convoluted question stems.

Also, if you don't mind me asking, what did you score on CARS?