てくださる

1. Origins, structure, and basic meaning

• Structure: Add くださる to a verb's て form to honor the person whose action benefits the speaker or the speaker's side.
• Basic usage: 先生が留学の推薦状を書いてくださった。 respectfully describes the teacher writing a recommendation letter.

2. Common pitfalls and similar expressions

• The honored agent and the recipient's viewpoint
  • In 先生が書いてくださった, the teacher performs the action; 私は先生に書いていただいた makes the recipient the subject. The person honored is the same, but the sentence viewpoint differs.
• Polite conjugation
  • The polite form of くださる is くださいます, and its polite past is くださいました. Distinguish the request 書いてください from the received help described by 書いてくださいました.