Question

英语补全对话中回答说I am going to...我可以用Where will yougo来问吗？

Answer 1

what are going to do?
What will you do?
What are you doing?
what are you to do?
What are you about to do?
这五种回答都是可以的，虽然有细微的区别。选择那种问法取决于你的语境和语意。
I am going to ........你可以简单理解为我要去.....
所以问题理应问他说你要去干什么，那就讲到未来时态将要做某事的五种表达方式。楼主可以百度一下，反正我是至今还没搞清楚。还羞耻啊，身为一个英语专业的学生。

Answer 2

不可以，当然不可以啊。
be going to 是将要/打算做某事，
应该用what are you going to do？来问。
where will you go?是你将要去哪里？
回答是I will go...
所以这两句问与答毫不相干。