だが— But / However (formal written)

• 試験は難しかった。だが、合格した。

  Shiken wa muzukashikatta. Daga, gōkaku shita.

  The exam was difficult. However, I passed.

  だが = but/however (formal), linking a contrast

• 努力はした。だが、結果は出なかった。

  Doryoku wa shita. Daga, kekka wa denakatta.

  I made the effort. But the results didn't come.

  だが opens a formal written contrast to the prior sentence

• 何度も電話した。だが、だれも出なかった。

  Nando mo denwa shita. Daga, dare mo denakatta.

  I called many times. However, no one answered.

  だが = but/however (formal), the calls went unanswered

• ・Formality: だが > しかし > でも > けど/けれど (most casual).
• ・Detail: だが is found in news articles, essays, and formal writing.
• ・Summary: It is rarely used in everyday speech.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones だが is tested against.

• のに (concessive) — The Frustrated "Despite"
• し — And also / What's more (listing reasons)
• それでも — Even so / Nevertheless / Still
• それで — So / Because of that / And then
• それに — In addition / Moreover