kanojo wa kanashii kao o shite ita.

She had a sad look on her face.

Breakdown of kanojo wa kanashii kao o shite ita.

• は: topic particle
• 〜て いる: progressive form
• 〜た: past tense
• 彼女かのじょ: she

Questions & Answers about kanojo wa kanashii kao o shite ita.

What does the pattern 顔をしている mean?

It literally combines 顔 (face) + を (object) + する (to do), but idiomatically it means “to have/wear/make [a kind of] expression.” So 悲しい顔をしている = “to be wearing a sad expression.” The 〜ている marks a continuing state; in the past, 〜ていた is a continuing state in the past.

Why is を used with 顔 instead of が?

Because 顔をする is a set idiom where 顔 is treated as the direct object of する. You “do” a certain face/expression. Using が here would be ungrammatical in this pattern. Compare: においがする (a smell occurs/there is a smell) uses が, but expressions with 顔 use を.

What’s the role of は in 彼女は?

は marks the topic: “as for her.” It sets “her” as the frame, and then tells you about her expression. If you used が (彼女が悲しい顔をしていた), you’d be emphasizing that it was she (and not someone else) who had that expression.

Why is it していた and not した?

〜していた (the past of 〜している) describes an ongoing state in the past—she was in that state of having that face. 〜した would suggest a single, momentary act: “she made a sad face (for a moment).” So 〜していた matches “was wearing/was looking” better.