Learn Hardcore Swahili: Kila siku ninajaribu kutumia msamiati huo katika sentensi nilizoandika mwenyewe. - Every day I try to use that vocabulary in the sentences that I wrote myself.

The noun after kila never takes a plural marker; kila itself carries the “plural” idea. So siku stays singular in form, even though the meaning is “days” in English.

What exactly is inside the verb ninajaribu grammatically?

ninajaribu is made of three parts:

ni- = “I” (1st person singular subject prefix)
-na- = present tense marker (roughly “am/is/are doing”)
jaribu = verb stem “try”

So ni-na-jaribu → ninajaribu = “I am trying / I try (now, nowadays).”

Can I also say najaribu instead of ninajaribu? Is there a difference?

Yes, you can say najaribu kutumia msamiati huo… and it’s very common in speech.

ninajaribu is the full form, slightly more careful/formal.
najaribu is a contracted form, very natural in everyday conversation.

Grammatically they mean the same thing in this sentence.

Why do we use another verb with ku- (like kutumia) after ninajaribu?

Swahili often uses a verb like kujaribu (“to try”) followed by another verb in the infinitive (the ku- form):

ninajaribu kutumia = I am trying to use
ninapenda kusoma = I like to read
ninaanza kufanya kazi = I’m starting to work

The ku- before tumia marks the infinitive / “to …” form of the verb. You cannot drop this ku- here; ninajaribu kutumia is the correct structure.

What does msamiati huo literally mean, and how is huo chosen?

Literally:

msamiati = “vocabulary”
huo = “that” (referring back to something already mentioned, in noun class 3)

So msamiati huo = “that vocabulary (we talked about / that specific set of words).”

huo is used because msamiati belongs to the m-/mi- noun class (class 3/4), whose demonstratives are:

huu = this
huo = that (near you / just mentioned)
ule = that (over there, more distant/remote)

So huo is the correct “that” to match msamiati.

Could I say msamiati ule instead of msamiati huo? Is there a difference?

You can say msamiati ule, and it is grammatically correct, but the nuance changes:

msamiati huo – “that vocabulary (we’ve just been talking about / that one near you in the discourse).”
msamiati ule – “that vocabulary over there / that (more distant or more emphatically separated) vocabulary.”

In most contexts where you’re referring back to vocabulary you’re learning or discussing, huo sounds more neutral and common than ule.

How does katika work here compared to other ways of saying “in sentences”?

katika is a preposition often meaning “in / within / inside (in a more formal or neutral way)”.

Here:

katika sentensi = “in sentences.”

You could also hear:

kwenye sentensi – also “in sentences,” a bit more colloquial.

In this context, katika is perfectly natural and slightly more standard/formal than kwenye, but the basic meaning is the same.

Is sentensi singular or plural in this sentence, and how can I tell?

Here sentensi is plural (“sentences”). Many loanwords like sentensi (sentence), simu (phone), televisheni (television) have the same form in singular and plural.

You know it’s plural in this sentence because the relative verb nilizoandika uses -zo-, the plural relative marker for class 10:

singular: sentensi niliyoandika = the sentence that I wrote
plural: sentensi nilizoandika = the sentences that I wrote

So the agreement on the verb tells you it’s “sentences.”

How is the form nilizoandika built, piece by piece?

nilizoandika breaks down like this:

ni- = “I” (1st person singular subject)
-li- = past tense marker (“did”)
-zo- = relative marker for noun class 10 plural (“which/that [are]”) agreeing with sentensi
andika = verb stem “write”

So ni-li-zo-andika → nilizoandika = “(that) I wrote”, with -zo- showing that the thing being talked about (the sentences) is the object being relativized.

Why is there no separate word like ambazo meaning “which” in sentensi nilizoandika mwenyewe?

Swahili has two common ways to form relative clauses:

Using a relative word like ambazo:
- sentensi ambazo niliziandika mwenyewe
  = “the sentences which I wrote myself.”
Using a relative marker inside the verb, as in your sentence:
- sentensi nilizoandika mwenyewe

Here, -zo- in nilizoandika does the job of “which,” so you don’t need ambazo. Both patterns are correct; the “built‑in” form (like nilizoandika) is very common and quite natural.

What exactly does mwenyewe add, and could it go somewhere else in the sentence?

mwenyewe adds emphasis similar to “myself” in English:

nilizoandika = that I wrote
nilizoandika mwenyewe = that I wrote myself (no one helped / I did it personally)

It usually comes after the verb phrase it emphasizes, so here it naturally follows nilizoandika. You could also place it after the subject pronoun in some contexts, e.g.:

Mimi mwenyewe niliandika sentensi hizo.
“I myself wrote those sentences.”

In your sentence, …nilizoandika mwenyewe is the most natural placement.

Since the sentence starts with kila siku, would it be better to use hujaribu instead of ninajaribu?

You could say:

Kila siku hujaribu kutumia msamiati huo…

Here hu- is a special habitual marker (no subject prefix before it), so hujaribu means “(he/she/one) usually tries.” However:

Kila siku ninajaribu… = “Every day I try / am trying…” (explicit I with ni-)

So if you keep kila siku plus hu-, it normally refers to he/she/one in a general sense, not clearly “I.” For “I” with “every day,” Kila siku ninajaribu… is the clearer and more typical choice.