Got back report book

Got back my report book today. Got 5 A1s(test 1&2) and fail 2 subjects. Thought I score quite well for my CA2.. Happily take my report book home. WTF!!!! They scolded me for my fall in marks.(comparing test 1 to 2) I shouted back and say, "Next time I score 0 for my test 1 lah. Confirm will improve one." Now got ban from using com.(but still can use if they not around)