词根：-vac-, -vacu-, -van-, -void-

【词根含义】：空

【词根来源】：-vac-来源于拉丁语动词vac.o, vac.are, vac.avi, vac.atum(空);-vacu-来源于拉丁语动词vacuo, -are, -avi, -atus(使空); -van-来源于拉丁语形容词van.us, van.a, van.um(空);-void-来源于古法语vuide(空的)。均可追溯至原始印欧语wan-(缺乏的)。

【同源单词】：vacancy, vacant, vacate, vacation, vacationist

前缀：a-

【词根含义】：在,到;来,临近;离开;否定;副词前缀;加强意义

【词根来源】：来源于古英语和中古英语a-, an, on。

【同源单词】：aboard, abroad, acentric, across, ago

词根词缀：a-, ab-, abs-

【来源及含义】Latin: prefix; from, away, away from

【相关描述】This prefix is normally used with elements of Latin and French origins (abs- usually joins elements beginning with c, q, or t).

The form ab- is regularly used before all vowels and h; and it becomes a- before the consonants m, p, and v. The prefix apo- has similar meanings.

This list is a very small sample of the multitudes of a-, ab-, abs- prefixes that are available in dictionaries and those in this unit are only meant to present a few examples.

【同源单词】abampere, abampere centimeter squared, abampere per square centimeter, abarticular, abarticulation, abbreviate