Dear Yong Peng,
I found I know nothing about words classified as "indeclinable".
Could you help me out of it?
How can I tell this word is "indeclinable", "preposition",
"participle" or sometimes so-called "adverb declinable"? [...sip]
Is "declinable" used as "adjective", "adverb" or "preposition" ?

Metta

Yifer