前缀ad-有十几种变体，分别是ac-,as-,af-,ag-,al-,an-,ap-,ar-,at-,a-,ad-是个构词能力很强，而又变化多端的原生词缀。它原是一个拉丁介词，意思相当于英语的to或at。在现代英语中ad-是个僵化词缀，它只能出现在与拉丁词根相结合而成的原始派生词中。前缀ad-和其他大部分前缀一样，会受到某些辅音字母语音变化的影响而出现辅音字母同化或辅音字母脱落等现象，这便有了ad-十几种变体。为了叙述方便，我们先介绍ad-的构词实例，然后再逐一讨论各种异体情况。

ad-出现在元音字母及d,h,j,m,v等字母之前。

1.adapt [ad-=to到；apt = to join 连→“连接到新环境去”→]
v.使适应；使适合
举例：Can you adapt your way of working to the new conditions?你能使自己的工作方式适应新的情况吗？

2.adequate [ad- = to 到；equ = equal 相等；-ate = to make 使→ 使与...相等→]
adj.适当的；足够的
举例：His wages are adequate to support his family.他的薪金足以养家。

3.adit [ad- = to 到;it=going 走→走到某地→]
n.途径；入口
举例：This is the only adit to the mine.这是到矿井的惟一入口。

4.adorn [ad- = to 到；orn = to equip 装配→“装配于....”]
v.使生色；装饰
举例：Wild flowers adorn the river banks. 野花点缀着河岸。

5.adult [ad- = to 到；ult = grown up 成长→“长大成型的”→]
adj.已经成熟的；已成年的
举例：The magazine is meant for adult readers.该杂志是面向成年的读者的。

6.addict [ad- = to 到；dict = to say 说→“对....表示赞成”→纵情于....→]
v.沉溺于，醉心于
举例：He addicted himself to gamble. 他赌上瘾了。

7.adhere [ad- = to 到；her= to stick 粘；-e→“粘到某物上”→]
v.粘附；依附，坚持
举例：Don't adhere to your own ideas when you are proved wrong. 既然证明你错了，就不要固执已见了。

8.adjacent [ad- = at 在；jac = to lie 位于；-ent adj. = -ing →“位于附近的”→]
adj.邻近的
举例：The house adjacent to ours has been sold.与我们相近的那座房子已经出售了。

下面举例说明ad-的异体ab-,af-,as-,ag-等的构词情况，请注意词根首字母的特点。

1.abbreviate [ab-(ad-) = to 到；brevi = short 短；-ate v. = to make 使→“使变短到某种程度”→]
v.缩写；简略
举例：We can abbreviate "Monday " to "Mon.". 我们可以将Monday 缩写成Mon.

2.affect [af-(ad-) = to 对；fect = to do 做 → to do sth. 对...做了某事→]
v. 影响
举例：The disease affected his memory. 那疾病影响了他的记忆。

3.arrive [ar-(ad-) = to 到；riv (rip) = shore 岸；-e→“到岸”→]
v.到达
举例：The train arrived at the station on time. 火车正点到站。

4.assist [as-(ad-) = at 在;sist = to stand 站→“站在某人身边”→]
v. 帮助
举例：She often assisted her mother with the housework. 她常帮助母亲做家务事。

5.attend [at-(ad-)= to 向；tend = to stretch 伸→“把手或心思伸向...”→]
v.注意
举例： Please attend to the baggage. 请留神这些行李。

6.aggress [ag-(ad-) = to 向；gress = to step 跨步→“向某人逼近一步”→]
v.攻击，挑衅；侵略
举例：Who aggressed in the fight? 是谁先动手打人的？

7.alleviate [al- (ad-) = to 对；levi = light 轻；-ate v. = to make 使→“使某事对某人的压力变轻”→]
v.减轻，缓和
举例：Try to alleviate the patient's suffering. 尽力减轻患者的痛苦。

8.annex [an- (ad-) = to 到；nex = to bind 绑→将一物绑到另一物上→]
v.附加，并吞
举例：The United States annexed Taxas in 1845.美国于1845年兼并了得克萨斯州这块土地。

9.appear [ap-(ad-) = to 向；pear (par) = to come →来→“向...走来”→]
v.出现
举例：A ship suddenly appeared on the horizon. 一艘船突然出现在天边。


ad-异ac- 可出现在c,k,q等读[k]的字母前面。

1.acclaim [ac<ad(=to) claim(=cry out)向某人大声叫喊]

vt.welcome someone with praise，joy，and applause along with loud shouts 欢呼，喝彩，极力称赞；

n.the act of doing this欢呼，喝彩，极力称赞；acclamation 喝彩，欢呼；

举例：The film debuted to widespread acclaim.

那部电影首映就收到广泛的赞扬。

2.accommodate [ac<ad(=to) com(=together) mod(=fit)使适合于某物]

vt. oneself to sth ;make fit;kindly give someone what he wants;have rooms for persons;reconcile disputes 适应；提供某人某事物；提供住宿，容纳；调节，使和解；

accommodation适应；住宿；住所；和解；accommodating亲切的；顺从的，迎合的；肯通融的；accommodative适应的；亲切的；

举例：The hotel staff made every effort to accommodate our least desire.

哪怕是我们提出的最小的要求，饭店职员也一样竭尽全力去满足。

3.acquit [ac<ad(=to) qui(=quiet)让某人心境平和]

vt.sb of sth;set someone free from a charge of crime or from duty;behave;conduct无罪释放；免除责任；立身处事；做出表现；

acquittal释放；表现；acquittance解除；债务的清理；

举例：The jury acquitted the prisoner after a short deliberation.

陪审团经过短暂的审议，决定无罪释放犯人。