Usually you add “ka” to the polite desu / masu form, but if you simply raise your tone at the end of a sentence, it becomes an interrogative statement or question. However, because this results in giving a somewhat impolite impression, it sounds a bit strange. (These are your clothes?): This makes it difficult to tell whether you are asking a question or not. (We shall go together?): This can sound as if you are being a little high handed. (This day is late?): This can sound as if you are dissatisfied. As it is unnatural to add “ka” when you are using a casual interrogative (such as what, who, when, or where), people might mistake your meaning. In this case use a raised intonation. (Who is coming?) (When shall we meet?) (Where is it?) Besides these, the following expressions are often used with a raised intonation as interrogatives or questions. Often used by women with the expectation of agreement or affirmation. Male language. With the expectation of agreement or affirmation. Confirmation. Asking about another person’s intentions. With the expectation of agreement. Male language. Used only to address one’s juniors. It includes a sense that you are uncertain of something or being pushy. It sounds like you are making a guess.