英文單字是許多考生最難以應付的題型，最快的進步方法就是要不斷背誦單字，讓自己的單字量增加，因此英銘老師特別把國考英文單字依據出題的頻率高低分層化，用不同顏色標註起來，透過例句補充，希望可以加強你對國考英文單字的記憶力喔！
( ) Every parent is aware of their infant’s tendencies to rapidly go _____ between sleep and wakefulness.
(A) in and out (B) up and down
(C) back and forth (D) inside and outside
always 此單字經常出現在國考英文試題當中，要特別注意！
often 此單字近2~3年內出現在國考英文試題當中。
sometimes 此單字近4~5年內出現在國考英文試題當中。
補充：
in and out 進進出出 (often)
Bruce has been in and out of prison for years.
Bruce多年來屢次入獄出獄。
up and down 上下地、到處 (always)
A bee is flying up and down among the flowers.
有一隻蜜蜂正在花叢裡忽上忽下地飛著。
I have been looking for my key up and down for nearly half an hour.
我到處尋找我的鑰匙，差不多找了有半個鐘頭了。
back and forth 來來回回地 (always)
April walked back and forth restlessly in the lobby.
April焦躁不安地在大廳走來走去。
inside and outside 內外 (sometimes)
Fires were started inside and outside the warehouse.
倉庫裡裡外外都著火了。
每個家長都瞭解自己的嬰兒在睡眠和清醒之間來來回回的傾向。所以答案是(C)。