1.breakfast用作不及物动词时意思是“吃早餐”,用作及物动词时意思是“向…供应早餐”,以供应对象作宾语。
2.breakfast用介词on引出早餐所吃的东西。

breakfast on(v.+prep.)
早餐吃… have breakfast by eating sth
▲breakfast on sth
We breakfasted on eggs and coffee.我们早餐吃的是鸡蛋和咖啡。

用作不及物动词
▲S+～(+A)
Olive had already breakfasted and gone out.奥利佛刚刚吃完早餐出去了。
They breakfasted early.他们早餐吃得早。
She came down to breakfast in a hurry, not having brushed her teeth.她匆匆忙忙地下楼吃早饭,连牙也没刷。
I'm going to breakfast with them tomorrow.我准备明天和他们一起吃早饭。
用作及物动词
▲S+～+n./pron.
The hotel regularly breakfasts 300 people.这家旅馆通常供应300人的早餐。
The restaurant breakfasted them during the exam.考试期间这家餐馆给他们提供早餐。

1.breakfast意思是“早餐,早饭”,指一天的一顿饭。是不可数名词。泛指早餐时,前面不加冠词; 特指某一顿早餐时还可加定冠词或其他限定词；有定语修饰且非特指时其前一般加不定冠词。
2.breakfast也可指“早餐吃的东西”,这时是可数名词。

They begin breakfast at seven.他们7点钟开始吃早饭。
I have hot cereal every day for breakfast.我每天早餐吃热粉粥。
We eat much the same thing for breakfast every day.每天早餐我们总是吃这些同样的东西。
Just as breakfast was completed there was a knock at the door.早饭刚刚吃完,外面就有人敲门。
It's a long time since breakfast.早餐以后已经过了很长时间了。
The next day she went to school without breakfast.第二天,她没吃早饭就上学了。
Cooking breakfast is her everyday job.做早饭是她的日常工作。
He had no money to buy a breakfast.他没钱买早点。
After quick a breakfast, he hurried to the station.他匆匆忙忙吃完早餐就赶到车站去了。
Thank you for the breakfast that you bought for me this morning.谢谢你今天早上为我买早点。
We had gruel for the breakfast.我们早餐吃的是麦片粥。
She bolted down her breakfast.她匆匆忙忙地吃了早餐。
We have our breakfast between seven and half past seven.我们在7点至7点半之间用早餐。
After that breakfast, she never saw him again.那顿早饭后,她就再也没见过他。

breakfast, dinner, lunch, meal, supper, tea
参见dinner条。

1.先生,早饭准备好了。
［误］  The breakfast is ready, sir.
［正］  Breakfast is ready, sir.
［析］  通常在一日三餐breakfast, lunch, supper前不加a或the。
2.那天是8点钟吃的早饭。
［误］  Breakfast was had at eight o'clock that day.
［正］  We had breakfast at eight o'clock that day.
［析］  have breakfast通常只用主动形式。

关于breakfast等一日三餐前冠词的用法,本词典的提法是泛指时“不加”冠词,有定语修饰或特指时“可加”冠词。也就是说特指某一次具体早餐时“也可不加”冠词。这主要是在以下两种情况:
1.上下文已表明是特指,例如:
That day breakfast was served on the terrace.那天,早饭是在阳台上吃的。
2.在介词after, before, during, for, at等之后。例如:
After breakfast she strolled into the vegetable garden.吃过早饭她到菜园子里去转了转。