In German, "wann," "seit wann," and "wie lange" are useful phrases for asking about time:

In German, "wann," "seit wann," and "wie lange" are useful phrases for asking about time:

1. **Wann**: This translates to "when." It is used to ask for the specific time or date something will happen.  

   - Example: "Wann beginnt das Konzert?" (When does the concert start?)

2. **Seit wann**: This means "since when." It is used to inquire about the starting point of an ongoing situation or action.  

   - Example: "Seit wann lernst du Deutsch?" (Since when have you been learning German?)

3. **Wie lange**: This translates to "how long." It is used to ask about the duration of an activity or event.  

   - Example: "Wie lange dauert der Film?" (How long does the movie last?)

### Summary:

- **Wann** = When

- **Seit wann** = Since when

- **Wie lange** = How long

These phrases are essential for asking questions related to time in German conversations.