Optional Lesson 4: Under the rug: A mess of particles and auxiliaries
These common important intermediate words aren't present in this guide. They're not present in any of the main lessons because they don't stick well into them, and because they're not particularly annoying.
Most of these are listing particles or emphatic particles that are hard to forget and easy to get a feel for. Let's sweep them under the rug.
なり can be a list marker that marks examples of possible options.
きり・っきり is a particle with two meanings.
In the pattern <noun>きり, it acts like an "only" marker.
In the pattern <statement>っきり, it basically means "ever since <statement>".
Some set phrases like 思いっきり, すっきり, てっきり, and はっきり contain the kana っきり, but aren't using the meaning described above.
やら is another particle with two meanings.
It can be used at the end of a statement to make an introspective question. This isn't just a modal particle, it can also be used in the middle of a statement, just like か.
It can also be used to list possibilities/examples, like か for alternatives.
こそ is an emphatic particle that acts a lot like stressing the word in english. In other words, it literally emphasizes whatever it attaches to. You can also think of it like "for sure" until it clicks in your head.
さえ is an emphatic particle that means "even an X", or "only an X", depending on the phrase and its polarity. まで can also be used this way, but not in negative/conditional phrases, and thus never means "only an X".
すら is a slightly literary emphatic particle very similar to さえ. すら can replace さえ when さえ means "even an X".
These sorts of "even an X" emphasis overlap with some uses of も and , which is why でも and だって were so hard to explain.
すぐ is an adverbial noun that means "immediately", either in a temporal way or in a spatial way. You can construct both "right in front of" and "right away" with it. すぐに basically means "soon".
ずつ is a particle that means "each" or "at a time". It emphasizes that the pace of something is steady, rather than just having an average rate.
がる is an auxiliary verb that means that someone other than the speaker (remember the "private predicate") shows signs of something. たがる is a combination of たい and がる, meaning someone looks like they want to do something.
がち is an auxiliary verb that means that someone or something has a tendency. The tendency is usually undesirable from an outside view.