1. contain / include

虽然都有“包含”的意思，但contain 可用于表示包含所含之物的全部或部分，而include则只能用于表示所包含之物的一部分。如：
The parcel contains a dictionary. 那包裹里装的是一本字典。
The parcel includes a dictionary. 那包裹里也包括一本字典。

2. energy / force / strength / power

energy通常指“精力、能源”讲；force通常指“武力、暴力、兵力”讲；strength通常指“ 力气、体力、长处”讲；power通常指“权力、能力、电力”讲。例如：
He is a man full of energy.他是精力充沛的人。
It took a lot of mental energy to understand his lecture.要想听懂他的讲座，必须动相当的脑筋才行。
It is important for a country to develop nuclear energy.发展核能对一个国家来说很重要。
He pushed the door open with all his force.他使尽全力推开那扇门。
We claim that we should settle international dispute by peace, not by force.我们主张解决国际事务应通过和平的方式而不是通过暴力手段。
He got his strength back slowly after his illness.他病后慢慢地恢复了体力。
Chinese is his strength. 他擅长中文。
The factory had to stop its production because of power failure.那家工厂因缺电而停产。
The police have the power to detain offenders.警察有权拘留犯人。

3. effect / affect / effort

effect名词：效果，功效，影响（后接on/upon…..）如：
His new way of teaching produced a good effect.他的新教法产生了良好的效果。
Scolding sometimes brings about an adverse effect on a child.责骂有时对小孩造成相反的效果。
The medicine had an instant effect on me.那种药对我立即有效。
come/go into effect生效 / bring / put… into effect 执行 / in effect事实上 / of no effect无效
affect 及物动词“对有……影响”，发生作用；（疾病）侵袭；感动。如：
Does the amount of rain affect the growth of crops? 降雨量会影响作物的生长吗？
The noise from the street affected our work.马路上的噪音影响我们工作。
The story affected us deeply.这个故事深深地打动了我们。
effort努力；尽力。如：
Getting a high grade in every subject requires great effort.想要每门功课都得高分需要非常的努力。
He did the work without effort.他毫不费力地做完了那件事。
I made every effort to get it.我竭尽全力想要得到它。
All his efforts were in vain.他所有的努力都白费了。
spare no effort 不遗余力

4. slim / thin

slim 通常指人或身体的部分的纤细和苗条以及（希望等）渺茫的，强调是健康的。而 thin 指人体时通常是指身体的单薄，瘦小，无力。指物时，通常指东西的“薄、细、稀薄”等。如：
She has a slim figure. 她身材苗条。
She is a girl with a slim waist.她有纤细的腰。
Our chances of success are slim. 我们成功的希望很渺茫。
He looks thin for his age.就年龄而言，他看上去很瘦小。
The higher you climb a mountain, the thinner the air becomes.山爬得越高，空气变得越稀薄。
Give me the thinnest thread, please.请给我最细的线。