"可以不 "and "不可以" are not the same meaning.今天晚上我可以不看電視。means :watching Tv or not is up to me.but 今天晚上我不可以看電視 means Can not watch TV (maybe the tv is broken)or watching tv is forbidden.

Why say 可以不， not 不可以 in this sentence？今天晚上我可以不看電視。 "今天晚上我可以不看電視" means "you choose if you want to watch TV tonight." you 【have】 the right to make your choice. but if you say"今天晚上我不可以看電視", that means "you can't watch TV tonight." you 【don't have】 the right to choose! 不可以＝you don't have right to choose do or not to do 可以不＝you can choose to do or not to do I hope I can help you! ^_<

可以不看電視 = It is possible I won't watch TV (for whatever reason). 不可以看電視 = I can't watch TV (basta).

"可以不" - may do or not do something. ----- Watching TV will be not necessary tonight(situation: you probably need to watch TV every night, but tonight). "不可以" - can't do somenthing. -------------- you can't watch TV tonight.

今天晚上我可以不看電視。 in this sentence , 可以不 cant be use as a words, they are apart .今天晚上我可以不看電視。 mean you can choice watch TV , 今天晚上我不可以看電視 ,mean you cant watch TV, and the decision is not you cant change, add. when "可以不" is put on the end,mean it is Question "可以不" can I ? is asking for the answer "不可以" mean you can't A:晚上我看下电视，可以不？ B:不可以。