dispensable

adj.可有可无的(unnecessary, unimportant)

This magazine is dispensable, so let’s discontinue our subscription.

这本杂志可有可无，我们停止订阅吧。

fortuitous

adj.偶然的，意外的 (accidental, coincidental)

He is not a good swimmer; he just won the gamefortuitously.

他不擅长游泳,他只是碰巧赢得了比赛。

haphazard

adj.偶然的；随便的 (casual, random)

I didn't mean to meet my old friend at the airport; it was just haphazard meeting.

我不是有意去机场接我的老朋友，这只是一次偶然的相遇。

lottery

n.碰巧之事

“Marriage is just a lottery, don’t believe in love. ”said the old man.

“婚姻就是彩票，不要相信爱情。”老人说。

occasional

adj.偶然的 (accidental, haphazard)

The silence was broken by an occasional scream.

一阵尖叫打破了寂静。

random

adj.任意的，随意的 (patternless, unplanned)

incidentally

adv.偶发性地（作为附带的或非主要的事）

My father was by profession a businessman and incidentally a musician.

我父亲的职业是商人，还是一名音乐家。

incidental

adj.偶发的(accidental)；临时的

decadence

n.衰落，颓废

The mayor criticized the teenagers for their decadence.

市长批评这些青少年的堕落。

decline

v.衰落(go down, drop)

As the dog grew older, its health declined.

随着年龄的增长，狗的健康状况每况愈下。

degenerate

adj.堕落的vi.退步(degrade, deteriorate)

I was shocked by the lack of morals in the degenerate book

我被这本堕落的书中缺乏道德所震惊。

degrade

vt.使降级(lower)；使堕落(degenerate)

I felt degraded by having to ask for money.

我因不得不向人要钱而感到自卑。