entries → 在於
TSUMUGU · TOCFL 6 (est.) · 詞
在於 word · TOCFL 6 (est.)
在於 =
ㄗㄞˋ ㄩˊ · zàiyú
verb — to lie in, to rest on, to consist in (the key point)

字源 FORM — what the parts do

to be at (存在)zài
at, in (relational particle)
在於,存在的在,於是的於。