Questions & Answers about Ich weiß genau, wann der Zug kommt.
German distinguishes two verbs for “to know”:
- wissen – knowing a fact, information, answer to a question
- Ich weiß, wann der Zug kommt. = I know when the train comes.
- kennen – being familiar with a person, place, thing, or situation
- Ich kenne den Zug. = I am familiar with / I know that train.
- Ich kenne Berlin gut. = I know Berlin well.
Here, you know a fact (the time when the train comes), so you must use wissen → ich weiß.
Ich kenne genau, wann der Zug kommt is wrong in standard German.
In German, a comma is mandatory before a subordinate clause.
- Ich weiß genau, → main clause
- wann der Zug kommt. → subordinate clause (introduced by wann)
So the comma is not optional style — German spelling rules require it: > Main clause , subordinate clause