“我原本打算今年寒假去新西兰游学, 顺便拜访你, 但很抱歉的是我不能来了”的英文翻译是:I originally planned to visit New Zealand for winter vacation this year and visit you by theway,but I'm sorry I cannot come.
Sorry, I can't make it this time. 意思是抱歉我来不了了。一般都只会说我来不了了,如果需要解释原因,再具体解释,如果直译 I have something to do. 很尴尬,也很奇怪。如果非要解释原因,比如 because i have some work to do. 或者 because i have a date with my friends.