Breakfast or lunch?

表时间频率，位于句首或句尾，实义动词前，非实义动词后

It was Sunday. I never get up early on Sundays.

常用的频率副词有： always总是；sometimes有时；often常常；never从来不；ever曾经，永远；rarely很少；seldom很少；frequently经常；usually通常；regularly定期地
那是个周日 我周日从来不早起。

never表示无条件的没有，意思相当于not，但两个词在用法上有区别:never后常接动词，而not表否定时前面一般需加助动词do,have等。
never get up. Do not get up.
She never said a word the whole tow hours.
get up = rise (rose 过去是 risen 过去分词)
I rose at 6 o'clock this morning.
每逢周日
on Sundays 词尾的s

I sometimes stay in bed until lunchtime.

sometimes = at times = 有时
Breakfast 早餐 Lunch 午餐 dinner 正餐(晚餐) supper 晚餐 meal 餐 snack 零食

Last Sunday I got up very late.

时间状语last Sunday 可以放句首也可以放句尾
I got up very lat last Sunday. 放句首更强调时间

比较一下
late: The airplane was late. 飞机晚点了
lately = recently 最近，近来 Have you been there lately? 你最近去过那里吗？
latest 最新的 The latest version 最新版本 The latest style 最新款式

I looked out of the window. 我向窗外望去

Look out 当心/ be careful
Look up 抬头仰视
Look after 照顾My friend looked after my cat while I was on holiday.
Look on 合看 May I look on with you ? 我可以和你合看(这本书)吗？

It was dark outside. 窗外一片漆黑

如果表示正在变黑 用进行时 It it getting dark outside. 夜幕降临

"What a Day!" I thought .

语言点 what引导的感叹句表示惊讶、愤怒、赞赏、喜悦等感情，具体的含义要根据说话者的语气或上下文的意思而定。What a day!语气为降调表示感叹“天气坏”，语气为升调表示感叹“天气好”。

"It's raining again"

表达下雨、下雪、踢球、读书等动作多用进行时态。
It is snowing in great flakes.
I'm reading a letter now.

Just then, the telephone rang.

Just then = just at that time/moment.

It was my aunt Lucy.

表亲友关系时，可以用“称谓+人名” 但如果是身份或职位时不可以这样表达，如“张老师”不能说成Teacher Zhang.

"I've just arrived by train.，”She said "I'm coming to see you"

by train / by airplane / by bike / by Car

瞬间性动词用于进行时态时表示即将开始的动作。
这些词主要有：come来；leave离开；arrive到达；land着陆；meet见到；die死；start开始；return 返回；join加入
He is leaving。他就要准备走了。
We are starting。我们准备开始了。

"But I'm still having breakfast", I said

still He came yesterday and he is still here. 他昨天来的，现在仍在这里。

"What are you doing" She asked

doing表示正在做某事，前句用having，此句用doing，问答一致

"I'm having breakfast" I repeated.

have一词多义 灵活 have lunch/dinner/snack 吃宵夜
eat 后跟比较干或厚的事务 美式的汤都是浓的 所以喝汤是 eat soup, eat sandwich/hamburger
drink 后跟稀一点的食物 比如 drink wine/tea/cola
吃药 是特殊的 要用take , Take medicine.
宝宝吃奶是 suck. My baby is sucking the milk.

repeat = say sth.again / 不能用repeat sth.again 错误的

关于英文符号
comma 逗号 period 句号 Colon冒号 dash 破折号 semicolon 分号
更多的参考下面

英语中常用的标点符号：comma逗号；period句号；colon冒号；semicolon分号；dash破折号；dots省略号；slash斜线号；parentheses圆括号；brackets方括号；apostrophe撇号；question mark问号；quotation marks引号；exclamation mark叹号