意外事故

• 夕(evening; crescent moon (pictographic))RADICAL
• 卜(divination; fortune-telling)PHONETIC

Evening outside divining fortunes under the moon — that's an external affair.

• ⼅(hook; fishhook)RADICAL
• 口(mouth; speech)ASSOCIATIVE
• 彐(hand holding brush)ASSOCIATIVE

Using your hand to hold a brush and write down important spoken words from beginning to end is work.

• 古(ancient; old)PHONO-SEMANTIC
• 攵(hand holding stick to strike)RADICAL

An old story remembered through the teacher's whip strokes is the reason and cause.