碰巧的英文：
by chance
by coincidence
happen to

参考例句：

Occurring by chance;fortuitous.
侥幸的碰巧发生的，幸运的

By coincidence I will go too, Let's go together.
碰巧我也去，咱们一同走吧。

I was browsing through a second-hand book store when I chanced on(upon)this old edition
我在一家旧书店里随意浏览，碰巧看到这种旧版本。

It happened to be a fine one that day.
那天碰巧天气好。

It happened that the harvest was bad in 1988.
碰巧一九八八年的收成很糟。

are you doing anything this evening, by any chance?
你今天晚上碰巧有事吗?

I happened to see her yesterday.
我昨天碰巧见到她。

I bumped into him by accident yesterday.
我昨天碰巧撞见他了。

I happened to know about him.
我碰巧了解他的情况。

"Coincidentally, he was also a teacher."
他碰巧也是名教师。

chance是什么意思：
n. 机会；可能性；偶然，侥幸
adj. 意外的，偶然的
v. 碰巧；偶然发生；偶然发现；冒...的险

I advise you to take the chance.
我建议你抓住机会。

outside chance; remote possibility.
不大可能的机会；极小的可能性。

I'll afford you a chance.
我将给你提供一个机会。

coincidence是什么意思：
n. 巧合；（意见等的）相同，符合，一致

coincident accidents
同时发生的事故

That was a really creepy coincidence.
那样的巧合实在太离奇了。

A series of coincident events.
一系列同时发生的事件。

happen是什么意思：
v. 偶然遇到；发生；出现；碰巧

These things will happen.
这种事总要发生的。

It happened far back in the past.
这事发生在久远的过去。

A string of accidents happened at that corner.
在那个转角发生了一连串的事故。