you are welcome to ask me unless you still have any questions.(单句改错)

问题描述:

you are welcome to ask me unless you still have any questions.(单句改错)
答案上只将unless改为if,为什么不将questions改为question?

any 任何一些,任何一个,后接单数名词或复数名词.根据句意思.如果你有任何问题都可来问我.应该是复数的问题.