1.by and by表示“没多久，一会儿之后，不久，马上”，相当于soon或after a while。

It's very likely to clear up by and by. 很可能不久要放晴了。

He'll come round by and by.

他会慢慢想通的。《汉英大词典》

By and by the school year will be over. 不多久这个学年就要结束了。

He'll be back by and by. 他一会儿就会回来了。

By and by you will learn a lot.

以后你会学到许多东西的。

I'll be there by and by.

我一会儿就来。

We'll meet again by and by. 我们不久又会再见。

They'll be arriving by and by. 他们不久就要到达.

By and by the clouds disappeared. 乌云不久便消散了。

2.by the by表示“顺便说到”，相当于incidentally，by the way。顺便提一下、“还有”等,用来引出一件补充或涉及所谈论的一般课题。

You said you would go to Changsha this afternoon, and by the by, which train are you going to take?

你说你今天下午要到长沙去,顺便问一下,你乘哪一趟火车去?

By the by，what happened to the boy？顺便问一下，那个男孩后来怎样了？

3.by and large表示“大体上，基本上，大致”。

By and large, the papers greet the government's new policy document with a certain amount of scepticism.

总体上，报界对政府的新政策文件将信将疑。

I tend to think that members of parliament by and large do a good job.

我个人觉得，议会议员总体上工作还是不错的。

By and large, I enjoyed my time at school.

总的说来，我在学校很开心。

By and large, the rules for healthy eating are the same during pregnancy as at any other time.

总的来说，怀孕期间健康饮食的原则和其他时期是一致的。

By and large, these people are peace-loving, law-abiding citizens.

大体上，这些人都是热爱和平、遵纪守法的公民。

By and large，the plan is practicable. 这个方案大体上可行。

They were, by and large, a very wealthy, privileged elite.

他们基本上是一些非常有钱有势的精英。

Taking it by and large, the conditions of employment are good.

从大体上说来，就业条件是好的。

4.gradually表示“渐渐地”，相当于slowly或little by little。

The weather gradually improved.

天气逐渐好转。

My mood gradually lightened.

我的心情渐渐好起来。

I gradually awakened to the realization that our marriage was over.

我逐渐意识到我们的婚姻结束了。

Gradually factory workers have been displaced by machines.

工厂的工人已逐渐被机器取代。

Gradually my depression started to lift.

我的沮丧情绪开始逐渐消失。

Their support gradually slipped away.

他们逐渐失去支持。

The water deepened gradually.

水渐渐变深了。

Gradually the pain seeped away.

疼痛渐渐消失了。

The flood waters gradually subsided.

洪水缓缓回落。

She's gradually turning into a Stepford wife.

她正逐渐变成一味顺从丈夫的妻子。

We watched their ship moving gradually farther away.

我们望着他们的船渐渐远去。

The weather gradually improved.

天气逐渐好转。

Gradually, the children began to understand.

孩子们渐渐开始明白。

The baby is gradually learning to walk. 那个婴儿渐渐地开始学走路。

Electricity lines to 30,000 homes were gradually being restored yesterday...

昨天，3万户家庭逐渐恢复了供电。

She gradually fought her way to the top of the company.

她努力奋斗，逐渐登上公司的高位。

They are gradually tapering off production of the older models.

他们在逐步减少生产旧型号的产品。

Gradually raise your body into an upright position.

慢慢起身，成直立状态。

The tension and excitement built gradually all day.

整个一天中，紧张与兴奋的气氛越来越浓。

The book starts slowly, but it gradually draws you in.

这本书开始时情节展开得很慢，但渐渐地就把你给完全吸引住了。

These changes were gradually assimilated into everyday life.

这些改变逐渐渗进了日常生活。

It is always prudent to start any exercise programme gradually at first.

刚开始一项锻炼计划时循序渐进总是明智的。

Sound him out gradually. Make sure it is what he really wants.

要慢慢地打探他的口风，要确保是他的心里话。