An action that moves a person or thing upward, or brings it to rest onto a surface.
序 · The move
1Pick the verb of the action (走, 爬, 穿, 貼).Is something rising, or coming into contact with a surface?
2Suffix 上 directly to the verb: 走上, 穿上.Does the path run up or onto, not down or off?
3Name what is climbed to or contacted right after 上: 走上樓.Is that noun the height reached or the surface met, not a separate destination trip?
例 · Examples
1他剛剛又走上walk up — 走 (walk) takes the upward direction via 上樓the upper floor — the height climbed to，不知去拿什麼東西。
He just walked up the stairs again, off to fetch who-knows-what.
界 · Boundary
V出 (directional 出)
上 sends the action up or onto a surface (走上樓, 貼上); 出 sends it outward from inside an enclosure (走出餐廳). One rises or sticks; the other leaves.
V到 (endpoint reached)
到 marks the point an action runs up to and stops at — a time, place, or amount (等到五點). 上 marks the upward direction or the surface contact itself, not a measured stopping point.
他走上去樓 ✗ → 他走上樓 ✓ (the bare place sits right after 上; 去 attaches only with no place named: 走上去)
English 'walk UP the stairs' or 'put ON a coat' uses a preposition before the noun; Chinese welds 上 onto the verb and the place or thing follows directly, with no preposition.