1.apt adj. 易于…的，有…倾向的
指天生具有做某事的倾向的，常后接动词不定式。
This kind of apple is apt to go bad.
这种苹果容易坏。
Iron is apt to rust.
铁容易生锈。
Jack is apt to be impulsive.
杰克易于冲动。
Babies are apt to put objects into their mouths.
婴儿爱把东西往嘴里塞。
The British prime minister is too apt to cling to Washington's apron strings.
英国首相对华府过于唯命是从。
She was apt to raise her voice and wave her hands about
她动不动就拔高嗓门，并挥舞双手。
This type of weather is apt to be more common in winter.
这种天气在冬季往往更为常见。
People are apt to confuse the two issues.
人们容易把这两个问题混淆起来。
2.liable adj. 易…的；易患…的
只作表语，指因习惯或倾向性而易做某事或产生某种问题、患上某 种疾病等的，常后接动词不定式或介词 to。多指负面的或不好的结果或状态。
The dog is liable to bite when angry.
这只狗生气时容易咬人。
we all be liable to make mistakes.我们总是容易犯错。
The college is liable to stop her scholarship because of her failure in the final exam.
由于她期末考试失败，学院有可能停了她的奖学金。
This area is liable to flooding.
该地区易遭受水灾。
He is liable to catch a cold.
他易患感冒。
He is liable to heart trouble.
他易发心脏病。
She will grow into a woman particularly liable to depression.
她长大成人后会特别容易患抑郁症。
Iron is liable to rust.铁容易生锈。
You are more liable to injury if you exercise infrequently.
不经常运动就更容易受伤。
Offenders are liable to fines of up to $500.
违者可能被处以最多500元的罚款。
3.likely adj. 可能的；可能（做…）的；有（…）倾向的
指可能发生或属实的，强调可能性。
Rain showers are likely tomorrow.
明天可能有阵雨。
What is the most likely cause of the problem?
造成这个问题最有可能的原因是什么？
Tickets are likely to be expensive.
入场券可能很贵。
Train fares are likely to remain unchanged.
火车票价很可能会保持不变。
Park illegally, and you're likely to be ticketed.
违章停车就可能收到罚款单。
In the meantime the war of nerves seems likely to continue...
与此同时，心理战似乎还可能继续。
The president appears likely to change course on some key issues.
总统看起来可能要在某些重要问题上改变方针。
These changes are likely to impoverish single-parent families even further.
这些变革很可能使单亲家庭更加贫困。
The report is likely to prove highly embarrassing to the government.
这份报告可能会让政府非常尴尬。
This decision is likely to upset a lot of people.
这项决定很可能会使许多人不快。
The increase is likely to hit the pocketbooks of consumers.
提价可能会砸到消费者的钱袋子。
The allegations are likely to damage his political career.
这些指控有可能伤及他的政治生涯。
The closure of the factory is likely to cost 1 000 jobs.
那家工厂一关闭，很可能1000个工作岗位就没有了。
They aren't likely to arrive this side of midnight.
午夜之前他们不大可能赶到。
He is hardly likely to admit he was wrong.
他不大可能承认自己错了。
The question of the peace settlement is likely to figure prominently in the talks.
和平解决的问题很可能是这次谈判的突出重点。
There are likely to be tensions and personality clashes in any social group.
任何社会团体都容易出现关系紧张和性格冲突。
The players' behaviour on the field is likely to bring the game into disrepute.
球员在赛场上的表现很可能使这场比赛臭名远扬。
He is likely to get off with a small fine.
他可能会逃脱严惩，仅仅罚一点钱了事。
The tension between the two countries is likely to remain
那两个国家间的紧张局面可能会持续下去。
Unemployment is likely to go on rising this year
今年的失业人数可能会继续上升。
The downward trend in home ownership is likely to continue.
拥有房屋所有权者人数减少的趋势可能会持续。
Education is likely to be a key issue in the next election.
在下届选举中教育可能成为最重要的一个议题。
You are likely to find many people who have stereotyped ideas about women.
你很可能会发现很多人对女性都抱有老一套的看法。
Attempts to limit family size among some minorities are likely to cause problems
试图在某些少数民族地区限制生育可能会引起问题。
The party is likely to divide along ideological lines.
该党有可能在意识形态上产生分歧。
They, too, would be likely to exact a high price for their cooperation.
他们也可能会为提供合作而索要高价。
4.prone adj. 有…倾向的，易于…的
基本相当于liable同义词。
尤指有发生不好或有害之事倾向的，通常作表语，常后接介词 to 或动词不定式。
He is prone to be/being late.
他容易迟到。
My mother is prone to headaches.
我母亲经常头痛。
Kids are mostly prone to eat junk food.
孩子大多喜欢吃垃圾食品。