a great/serious/terrible mistake

...spelling mistakes.

拼写错误

I think it's a serious mistake to confuse books with life...

我认为把书本同生活混为一谈是大错特错。

I mistook you for Carlos...

我把你错当成卡洛斯了。

It would be a mistake to ignore his opinion.

忽略他的意见是不对的。

Children may eat pills in mistake for sweets.

孩子们会把药片错当成糖果吃的。

Don't worry, we all make mistakes .

没关系，我们都会犯错。

This is a strange business and no mistake.

这确实是件怪事。

They made the big mistake of thinking they could seize its border with a relatively small force...

他们大错特错，居然认为以较少的兵力就能够夺取其边境地区。

The government completely mistook the feeling of the country...

政府完全没有把握住该国民意。

I admit that I mistook his intentions.

我承认我误解了他的意图。

The waiter made a mistake (in) adding up the bill.

服务员结账时算错了账。

It's a common mistake among learners of English.

这是学英语的人常犯的错误。

Her essay is full of spelling mistakes .

她的文章到处都是拼写错误。

I made the mistake of giving him my address.

我真不该把我的地址给他。

This letter is addressed to someone else─there must be some mistake.

这封信是给别人的——一定是搞错了。

I mistook her offer as a threat.

我把她的好心错看成威胁了。

There's no mistaking the eastern flavour of the food...

那种食物就是东方风味，绝对错不了。

Leaving school so young was the biggest mistake of my life.

我一生中最大的错误就是那么年轻就离开了学校。

It's a common mistake (= one that a lot of people make).

这是常犯的错误。

Make no mistake (about it), this is one crisis that won't just go away.

要知道，这是一场不会自行消失的危机。