偶然的英文：
incidentally
occasional
occasionally

参考例句：

Happening by chance or accident;fortuitous.
偶然的偶然或意外发生的;偶然的

An accidental or unpredictable event.
偶然的事，意想不到的事

The occurrence of such things is by no means fortuitous.
出现这种问题绝不是偶然的。

The occurrence of such things is by no means fortuitous
出现这种问题绝不是偶然的。

He happened on the book in a secondhand bookstore
他在旧书店偶然发现了这本书。

Chance had chucked us together at a skiing resort.
偶然的机缘使我们在一个滑雪胜地相遇。

Justice is incidental to law and orde.
对于法律和秩序，公正是偶然的。

Their accidental meeting led to a renewal of their acquaintance.
偶然的相遇使他们重续前缘。

Sam struck on that anthology in a second hand book store
萨姆在一家旧书店里偶然发现了那本选集。

I found out by chance that she was actually a freshman from London University.
我偶然发现她实际上是伦敦大学的一年级学生。

incidentally是什么意思：
adv. 顺便；偶然地

Justice is incidental to law and orde.
对于法律和秩序，公正是偶然的。

Loss is incidental thing.
迷失是容易发生的事。

That is incidental to my story.
那是我故事中的附带事件。

occasional是什么意思：
adj. 偶然的；临时的；特殊场合的

Friends visit them occasionally.
朋友偶尔拜访他们。

It occasionally produces luscious peaches.
它有时会结出些甘甜的桃子来。

If the occasional camper drove along.
偶尔有些露营者路过。

occasionally是什么意思：
adv. 偶尔，间或

Friends visit them occasionally.
朋友偶尔拜访他们。

It occasionally produces luscious peaches.
它有时会结出些甘甜的桃子来。

If the occasional camper drove along.
偶尔有些露营者路过。