grammar → 對…有興趣
TSUMUGU · TBCL 3 (est.) · 語法
對…有興趣 grammar point · tier 1 · interest in X: 對…有興趣 (be interested in)
Front 對 to aim at a target, then say 有興趣 (have interest) about it: be interested in X.

字源 FORM what the parts do

對 turns the speaker to face a target, the way a held-up tablet turns to answer the one who asked. 有 holds the feeling in hand. 興 is many hands heaving a thing up; with 趣, whose legs (走) run toward what pulls them, the pair 興趣 is the lift of being drawn. The target named after 對 is the thing the legs run at.

故事 STORY a scene to remember it by

A face swings round to fix on one thing; once it is fixed there, the legs are already running that way.
字源記憶法
框 · Frame
[subj] 對 [target] (很/沒) 有興趣
觸 · Trigger
You want to name what someone is drawn to, and point the interest at that thing.
序 · The move
1Say the person, then 對.Is the next slot the thing drawn-to, not the feeling?
2Name the target right after 對.Does the target sit between 對 and 有興趣, not after it?
3Close with (很/沒)有興趣.Degree word 很 sits before 有興趣, not before the target.
例 · Examples
1toward畫畫drawingvery有興趣have interest,以後想當畫家。
He is very interested in drawing; he wants to be a painter one day.
界 · Boundary
喜歡
喜歡 takes the target as a bare object (喜歡畫畫); 對…有興趣 must front 對 before the target and park the feeling at the end.
對…感興趣
Same 對-fronted shape; 感興趣 fuses feel+interest into one verb, 有興趣 keeps 有 as 'have'. Both aim at the target the same way.
他很有興趣畫畫。 ✗ → 他對畫畫很有興趣。 ✓ (target rides after 對, not after the feeling)
他興趣對畫畫。 ✗ → 他對畫畫有興趣。 ✓ (對 leads to the target; the interest closes the line)
他對畫畫有很興趣。 ✗ → 他對畫畫很有興趣。 ✓ (很 modifies 有興趣 as a unit; it sits before 有)
English 'interested in X' puts the preposition after the feeling; Chinese fronts 對 before the target and saves 有興趣 for the end.