質問: 英語の試験はいつか知ってる? と 英語の試験はいつ知ってる? はどう違いますか? 英語の試験はいつか知ってる? と 英語の試験はいつ知ってる? はどう違いますか?
回答: the latter sentence's "いつ" is an adjective that modifies "知ってる". as a general japanese, we don't say in that way. the former is the true expression. that case's "いつ" is used predicatively. the only difference of two sentences is the presence of "か", so this question is a little bit difficult to answer.