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：memor-, memen-

【来源及含义】Latin: memory, remember, thought; retaining and recalling past experiences and information; capacity to store information; ability to recall or to recognize previous experiences; recollection; retention

【相关词根词缀】 Related "forget, forgetfulness" word families: aletho-; letho-; oblivio-. Related "memory, remembering" word families: mne-; reminisc-.

【同源单词】Ad perpetuam rei memoriam, Aequam memento rebus in arduis servare mentem, cache, cache memory, commemorate, commemoration

词根词缀：per-

【来源及含义】Latin: through, across, over; beyond, by means of

【同源单词】Ad astra per aspera, Ad augusta per angust, Ad perpetuam rei memoriam, Ad virtutem per sapientiam, ampersand, antiperspirant

词根词缀：peti-, pet-, -pit-

【来源及含义】Latin: to aim at, aim for, go toward; to seek, seek out, ask, request; strive after

【同源单词】Ad perpetuam rei memoriam, appetence, appetency, appetent, appetently, appetite