Do you know why the train_____ _____?请问是填was late 还是 is late?3Q

Do you know why the train_____ _____?请问是填was late 还是 is late?3Q
1.Do you know why the train_____ _____?请问是填was late 还是 is late?
2.I didn't know______he was waiting for.是填 who that whom
3.He asked______________________________.
A which picture John's was.B which picutre was Joan's