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。由于语音同化的影响，ad-有11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的情况。 

ad-出现在元音字母及d，h，j，m，v等字母之前。

adapt [ad- = to 到; apt = to join 连=> “to join to a new place 连到新环境去”→] v. make fit; adjust使适应；使适合/ 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？

adaptation n. 适应；适合 

adaptive a. 适应的；适合的

adequate [ad- = to 到；equ = equal 相等；-ate = to make 使=>“to make equal to 使与…相等”→] a. as mush as is needed; enough 适当的；足够的/His wages are adequate to support his family. 他的薪金足以养家。

adit [ad-=to 到；it=going 走=>“a going to a place 走到某地”→]”n. approach; entrance 途径；人口 / This is the only adit to the mine.这是到矿井的惟一入口。

adorn [ad- = to 到；orn = to equip 装配=>“to equip to 装配于…”→] v. add beauty to; decorate 使生色；装饰 / Wild flowers adorn the river banks.野花点缀着河岸。

adornment n .装饰；装饰品