Tom has to wear a uniform today.(就划线部分提问）划线部分是a uniform

题目

Tom has to wear a uniform today.(就划线部分提问）划线部分是a uniform

答案

a uniform 是物,并且没有涉及需要选择的问题,所以不用which,用what 提问.
答案是 What does Tom have to wear today?