Don’t use commas
Between an independent clause and a dependent, restrictive clause
- Das Buch, das Heinrich Zimmer geschrieben hat, kostet 30 DM. Restrictive: The book that Heinrich Zimmer wrote costs 30 DM. Nonrestrictive: The book, which Heinrich Zimmer wrote, costs 30 DM.
Before modified infinitive clauses
- Ich versuche, weniger Bier zu trinken. Incorrect: I’m trying, to drink less beer. Correct: I’m trying to drink less beer.
Before infinitive phrases with “um...zu,” (in order to) “ohne...zu,” and “anstatt...zu” (instead of)
- Er ging zur Polizei, um seinen Paß abzuholen. Incorrect: He went to the police, in order to pick up his passport. Correct: He went to the police in order to pick up his passport.