Präsens
What is happening now, habits, and plans: morgen fahre ich.
- es donnert
to thunder
Weak verb, auxiliary haben.
Conjugated like klettern, rumschlendern, sich verändern, zusammenfeiern, zumauern, liefern
es
This verb has no other subject than es.
Enough to talk about now, your plans, and what you did.
What is happening now, habits, and plans: morgen fahre ich.
The everyday past in speech: haben or sein plus the participle.
The past of stories, books, and the news. In speech, the Perfekt is more common.
Polite requests, wishes, and what would happen: ich würde gern…
Promises, predictions, and guesses about now: das wird stimmen. The present often says the future: morgen fahre ich.
A past action completed before another past action.
Hypotheses and wishes in one word. In speech, würde + infinitive replaces it, except for common verbs: käme, ginge, wüsste.
What would have happened, and regrets: wenn ich das gewusst hätte…
Reported speech, in the news and in writing, mostly with er, sie, es: sie sagt, er sei krank.
An action finished before a future moment, or a guess about the past: er wird es vergessen haben.