…以內/以外/以東/以西…（位置）grammar point · tier 2 · spatial bound 以內/以外/以東/以西… (the side of a line or landmark)
Takes a physical line, road, or landmark as the reference, then names which side of it is meant: 以內 the side inside it, 以外 the side past it, 以東/以西/以南/以北 the compass side of it, 以左/以右 the side to its left or right.
字源 FORM what the parts do
The landmark before 以 is the line drawn on the ground. 以 takes that line as the point to measure from. The direction word names the side: 內 the side enclosed within it, 外 the side beyond it, 東/西/南/北 the compass quarter off it, 左/右 the hand's side of it.
故事 STORY a scene to remember it by
A line is drawn across the map. 以 stands on it; the side word shades one side and leaves the rest blank — the shaded ground is meant, the line itself and the far side are not.
字源記憶法
框 · Frame
[landmark / line / road] + 以 + {內|外|左|右|東|西|南|北}
觸 · Trigger
You have a fixed line or landmark on the ground and you mean the region on one side of it.
序 · The move
1Fix the reference that draws the line: a road, a river, a marked line, a landmark (黃線, 這條河, 和平東路).Is it a thing on the map you could draw a line along — not a number on a scale?
2Pick the direction word for the side you mean.Enclosed within → 內; past it → 外; a compass quarter → 東/西/南/北; a hand's side → 左/右.
3Set the reference first, then 以, then the direction word, the three glued tight as 河以東 / 線以內.No measure word between 以 and the direction; the landmark leads, 以X trails.
例 · Examples
1捷運站MRT station黃線the yellow line以內inside (this side of the line)的範圍area; range不能cannot吃東西eat。
Inside the yellow line at the MRT station, you cannot eat.
The spatial use takes a physical line on the map — a road, a river, a marked line — and names a side of it, so it admits compass words 東/西/南/北 and 左/右. The scalar use takes a number, age, or price on a scale and names a span above or below it; it never takes a compass word.
河的東邊 / 線的裡面 (bare 的 + side word as plain location)
以東/以內 set the landmark as a boundary and name the open region off it. 河的東邊 names the bank that belongs to the river, the spot beside it; 河以東 names the whole territory east of the river's line.
黃線內 ✗ → 黃線以內 ✓ (the boundary sense needs 以; bare 內 reads as merely physically inside the object)
這條河以左 ✗ → 這條河以東 ✓ (a fixed map landmark takes the compass word, not a viewer-relative 左/右)
English puts the side word first — east of the river, inside the line — so learners reach for the direction ahead of the landmark, or drop 以 and write the bare side word. Chinese fixes the landmark first, then 以, then the direction: 河以東, 線以內.