词根：-ced-, -cess-, -ceed-

【词根含义】：行走,退让

【词根来源】：来源于拉丁语动词cedo, cedere, cessi, cessus (行走,退让)。

【同源单词】：accede, antecede, antecedent, concede, intercede

前缀：ac-

【词根含义】：来,临近;加强意义

【词根来源】：ad-的变体,用在c前。

【同源单词】：accede, accelerate, acceleration, accelerator, accelerometer

词根词缀：ad-

【来源及含义】Latin: prefix; to, toward, a direction toward, addition to, near, at; and changes to: ac-, af-, ag-, al-, an-, ap-, aq-, ar-, as-, at- when ad- is combined with certain words that begin with the letters c, f, g, l, n, p, q, r, s, and t

【相关描述】The form ad- appears in this form before a vowel and before the consonants d, h, j, m, and v. It is simplified to a- before sc, sp and st.

Before c, f, g, l, n, p, q, r, s, and t; ad- is changed to ac-, af-, ag-, al-, an-, ap-, aq-, ar-, as-, and at-.

In other words, the d of ad usually changes into the same letter as the first letter of the following root or word when it is a consonant: ad-fix becomes affix, and ad-sign becomes assign; therefore, making a double consonant.

Another example includes: attract as with ad-tract (drawn towards); so it has a double t. On the other hand when ad- precedes a vowel, as with adapt, it is simply ad-apt, with one d. For the same reason, there is only one d in adore and adumbrate, because ad- has combined with orare and umbra each of which starts with a vowel.

So, remember: since these Latin words begin with vowels and not consonants, the d of ad does not double as shown in the previous examples.

【同源单词】a capite ad calcem, Ab ovo usque ad mala, Ab uno ad omnes, Abiit ad majores, abjure, accede

词根词缀：-cede, -ceed, -cess, -cease

【来源及含义】Latin: to be in motion; to go, to go away, to yield, to give up, to withdraw

【同源单词】abscess, accede, access, access, accessibility, accessible