所…所…【suǒ…suǒ…】

所 in front of a one-syllable verb turns it into "what is V-ed": 所见 is "what one sees". Two such pairs side by side make one noun phrase covering everything of both kinds. The pair works as subject or object like any noun, and the person it belongs to goes in front with 的.

The set pairs

A handful of pairs cover almost every case, and each has its own colouring:

• 所见所闻 – what one saw and heard; neutral, for travel writing and reports
• 所作所为 – what one did; usually critical, about someone's conduct
• 所思所想 – what one thinks and feels
• 所言所行 – what one says and does

To praise what someone did, use 做法 instead of 所作所为.

Building the pair

Both verbs are one syllable, and nothing goes between the two halves. A two-syllable verb or a 的 in the middle breaks the pattern.

• × 所看见所听见 → 所见所闻
• × 所见的所闻 → 所见所闻

The single-verb version, 所 + verb + 的 + noun (我所知道的事), is its own point (所…的).