事故は我々が油断している時に起こるものだ。

Accidents will happen when we are off guard.

事故(じこ)は我々(われわれ)が油断(ゆだん)している時(とき)に起(お)こるものだ。

Jiko wa wareware ga yudanshiteiru tokini okoru mono da.

事故 (じこ、ことゆえ)

accident; incident; trouble; circumstances; reasons

は (は)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

我々 (われわれ)

が (が)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

油断 (ゆだん)

negligence; carelessness; inattention; unpreparedness

時に (ときに)

by the way; incidentally; sometimes; occasionally

起こる (おこる)

to occur; to happen

者 (もの、もん)

person

だ (だ)

be; is; indicates past or completed action; indicates light imperative

Readings: ジ、ズ、こと、つか.う、つか.える

Meanings: matter, thing, fact, business, reason, possibly

Readings: コ、ゆえ、ふる.い、もと

Meanings: happenstance, especially, intentionally, reason, cause, circumstances, the late, therefore, consequently

Readings: ガ、われ、わ、わ.が-、わが-

Meanings: ego, I, selfish, our, oneself

Readings: ユ、ユウ、あぶら

Meanings: oil, fat

Readings: ダン、た.つ、ことわ.る、さだ.める

Meanings: severance, decline, refuse, apologize, warn, dismiss, prohibit, decision, judgement, cutting

Readings: ジ、とき、 -どき

Meanings: time, hour

Readings: キ、お.きる、お.こる、お.こす、おこ.す、た.つ

Meanings: rouse, wake up, get up