If you remove “ma” from the sentence above, you still have a sentence, but a afermative one, ma is the chinese question mark (funny it is the character of a mouth and a horse, never look a given horse in its mouth, i.e. don’t ask questions and use “ma” :-) …). Instead of using ma you could also say “wo keyi bu keyi yong xin yong ka” By the way I don’t understand yong ka, pehaps you meand kuai zi = chopstiks
In characters it looks like this:
我可以用新筷子吗 OR 我可以不可以用新筷子
我可以用新筷子 simply means I can use new chopsticks.

I hope I have answered your answer correctly, I am sure Benny and his angels can help you to answer your questions.

Roland 陆蓝克