I use the book as my main learning source, and in "The war between (wa) and (ga) there is an example question that says:
- なにいro が すきですか。
My question is: do I have to always use が when saying なにいro ? Because in Lesson 4, が isn't used when asking:
- なにいro ですか。
- なにいro no くruma ですか。
And so. Hope you answer me. Thanks a lot mr. professor!