kudasai ください

Polite command form meaning: please give... to me, please do something (for me)

1. After noun + o
八時に電話をください。
Hachi ji ni denwa o kudasai.
Please give  me  a call at eight.
このズボンをください。
Kono jaketto to zubon o kudasai.
Please give me this jacket and these pants. (I'll take this jacket and these pants.)

2. After te-form of verb
この漢字の書き方を教えてください。
Kono kanji no kakikata o oshiete kudasai.
Please teach me how to write this kanji.

3. After nai-form of verb + de
まだ行かないでください。
Mada ikanai de kudasai.
Please don't leave yet.

-> See also kureru, Polite Language (2)