This paper argues that the view from stricter syntactic parallelism fails to explain why sluicing in Amis can tolerate morphological and structural mismatches caused by argument structure alternations or pseudocleft/non-pseudocleft distinction as well as a violation of the generalization on preposition stranding (Merchant 2001). Building on these facts, we propose that all these mismatches can be captured by semantic isomorphism entertained by Merchant (2001), i.e. the Focus condition on IP-ellipsis with some extension to VP-ellipsis. Both conditions are incorporated to cope with the IP-ellipsis of the pseudocleft sluice and the VP-ellipsis of the serial verb sluice in Amis. Structurally, the whole sluice clause is unanimously topicalized in Amis before the ellipsis of IP or VP within the base-generated sluice interrogatives. Theoretically, Amis sluicing strictly adheres to the mutual entailment of e-GIVENness, while the eclectic lexico-syntactic approach adopted by Chung (2005a) is untenable.