Requests, time & plans
Formal imperatives use the verb + Sie. Du imperatives often use the stem; common irregular: sein → sei. Möchten and könnten make polite requests. Use seit + present for something still ongoing. Present tense with a future time phrase can express a plan.
Understand the idea
Polite requests, ongoing situations and future plans often use familiar grammar in a particular way. A formal instruction has a different structure from a du command. German also uses present tense in situations where an English translation may use a perfect or future form.
Build it step by step
For formal instructions, place the infinitive-shaped verb before Sie. Use a Konjunktiv II request such as könnten for extra politeness. With seit and an activity continuing now, present tense is normal. A time phrase such as morgen can make a present-tense sentence refer to a planned future event.
See it in a sentence
Könnten Sie mir bitte helfen?
Ich lerne seit einem Jahr Deutsch.
A useful memory aid
Learn a polite request as a reusable sentence frame, then change its object or infinitive. For time, establish whether the situation is still continuing now.
A common trap
Do not copy English tense choices word for word. Since does not automatically require a German compound past, and a future time expression does not always require werden.