一定要改的,what are you going to use? how are you going to use it?
疑问句都是根据原本的陈述句改的,只要把这两个句子还原成陈述句就知道疑问句对不对了,比如用what,改为陈述句就是you are going to use what. 所以你给的例句多了一个it,因为那样样改过来就是you are going to use it what,既有it又有what当然不行,他们做的成分都是use的宾语所以重复了,而用how就行了,就是how you are going to use it,it做use的宾语,而how是表示动作进行的方式,两个不重复.