Focus, topic, cleft

kú, bï, and nä are three particles that serve closely related pragmatic functions. Let’s examine the ways in which they differ.

Main use

kú	bï	nä
Identify the foreground, foremost important part of what you’re saying.	Identify the background – the pivot on which you’re making your point.	Rearrange words.
Example
As for apples, because I dislike sweet ones, I like savory ones best.
I want you to know it’s flavor we’re talking about, and it’s the savoriness that I care about in apples.	I want you to know that I’m going to be talking about apples.	I didn’t feel like saying I like savory ones best because I dislike sweet ones, in that order.

Syntax

kú	bï	nä
Goes in front of the phrase you want to foreground. As a prefix (ku-), attaches to the single word you want to foreground.	topıc bï, comment. topic must be a definite noun phrase, like the cat or that I love you. If you want to refer back to the topic, you may not use hóa, but you may use any of the other strategies available to you, like máq or hụ́ꝡa.	noun phrase nä relatıve clause. clause must refer back to the noun phrase, either using hóa or an appropriate pronoun like hó or hụ́ja.
		adverbıal nä clause. In this usage, hóa is not used because there’s nothing to refer back to.

Gotchas

• Focus is often rendered as an English cleft in translation: Shao paı jí kú súq It’s you who I want to be friends with. However, Toaq clefts do not impart focus: Súq nä shao paı jí hóa is just a convoluted way of saying Shao paı jí súq. You may, however, use the two features in tandem: Kú súq nä shao paı jí hóa.
• For noun phrases, bï does not bind hóa. You must use another anaphoric pronoun if you want to refer back to the topic. The crucial difference is that bï’s complement, the topic established, is not required to appear in the clause! So for example, this is valid Toaq (and valid English, although some languages like Japanese like this pattern better than English does) and the extra specification in square brackets is not required at all:

  Báq kası bï, he duq garabıa jí [gêm máq].

  As for walnuts, I tend to get nausea [from them].