Learn Hardcore Swahili: Usiku, mimi natumia tochi kutembea kwenye njia. - At night, I use a flashlight to walk on the path.

Yes. In Swahili the subject is already marked in the verb, so mimi is optional. You add mimi mainly for emphasis or contrast (as in “Me, I use a flashlight…”). Neutral, natural speech would be: Usiku, natumia tochi kutembea kwenye njia.

Should it be natumia or ninatumia?

Both are correct. Ninatumia is the full form (subject prefix ni- + present marker -na- + verb), while natumia is the very common contracted form where the extra syllable is dropped. In everyday speech and writing, natumia is perfectly fine.

What does each part of natumia mean?

(Underlying) ni- = I (subject prefix)
-na- = present/ongoing or general present
tumia = use (verb stem) Full form: ni-na-tumia → ninatumia; contracted: natumia.

Why is it kutembea here? What does the ku- do?

Ku- makes the infinitive/gerund (“to walk/walking”). After verbs like tumia (use), the infinitive expresses purpose or the activity: natumia tochi kutembea = “use a flashlight to walk.”

Could I use ili instead of just kutembea to express purpose?

Yes, but it changes the structure slightly:

Simple infinitive of purpose: natumia tochi kutembea (very common).
With ili (“so that/in order that”): natumia tochi ili nitembee. After ili, use the subjunctive (nitembee, not ninatembea).

Do I need kwa before kutembea (e.g., kwa kutembea)?

No. Kwa kutembea is possible but sounds like “by means of walking,” which shifts the meaning. For “use a flashlight to walk,” the bare infinitive kutembea is the natural choice.

Why kwenye njia? Could I say njiani or barabarani?

kwenye njia = on the path/way (neutral, very common).
njiani = on/along the way (using the locative suffix -ni; very idiomatic).
barabarani = on the road (vehicular road). All are correct; pick the one that matches the setting. Many speakers would naturally say …kutembea njiani.

Is kwenye a preposition that changes with noun class?

No. Kwenye is invariable (works like “in/at/on”). It doesn’t take agreement. If you add adjectives to njia, those would agree with the N-class (e.g., njia ndefu).

Does njia have a plural?

Yes, but it looks the same. Njia is N-class: singular = plural. Context (or numerals/determiners) tells you whether it’s one or many.

What exactly does tochi mean? Is it “torch” or “flashlight”?

In East African Swahili, tochi is a flashlight (British “torch”). It’s a loanword. It’s N-class too: singular and plural are both tochi.

How would I say “my flashlight”?

tochi yangu (possessive agrees with N-class). Demonstratives follow the noun: tochi hii (this flashlight), tochi zile (those flashlights).

Should there be an object marker in the verb for tochi?

Not when the object is stated right after the verb. If you replace the noun with a pronoun “it,” you can use the class 9/10 object marker -i-: naitumia = “I use it.”

Can I move Usiku to a different position?

Yes. Time expressions are flexible:

Usiku, natumia… (time first for emphasis)
Natumia tochi… usiku. Both are natural.

Is the comma after Usiku necessary?

No. It’s stylistic. Many writers omit it. The pause in speech is enough.

How do I make the sentence negative?

Use the negative subject prefix and change final -a to -i:

situmii tochi … = I don’t use a flashlight … Full example: Usiku, situmii tochi kutembea kwenye njia.

How do I say it in past or future?

Past (marker -li-): nilitumia tochi…
Future (marker -ta-): nitatumia tochi… Tense markers slot where -na- sits in the verb template.

What’s the difference between usiku, usiku huu, and usiku wa leo?

usiku = at night/in the nighttime (general).
usiku huu / usiku wa leo = tonight (this specific night). Use one of these if you mean “tonight.”

Any pronunciation tips for kwenye and njia?

kwenye: pronounce ny as the single palatal nasal (like Spanish ñ): kwe-nye.
njia: start with a clear “nj” cluster before “ia”: n-jia (two syllables: nji-a).

Is there a more colloquial way to say the same idea?

Yes, very natural alternatives include:

Usiku, natembea njiani nikiwa na tochi. (I walk on the way at night while having a flashlight.)
Usiku, natumia tochi kutembea njiani. (Swaps in the -ni locative.)