acre n. 英畝
(類)ream·paper=acre·land 紙的單位·紙=畝·土地
acquit vt. 宣告無罪(to free or clear from a charge or accusation)
acrid adj. 辛辣的，刺鼻的(sharp and harsh in taste or odor)
(類)acrid·odor=grating/ piercing·sound 刺激的·味道=刺耳的·聲音(形修飾名)
acrid·gentleness=forthright·guile 辛辣的·溫和的=直率的·狡詐(反面特征)
(反)acrid
◆ gentle 辛辣的
◆ 溫和的
acrimonious adj. 刻薄的(caustic especially in feeling, language, or manner)
(反)acrimonious
◆ harmonious 刻薄的
◆ 和諧融洽的
(記)acri(尖，酸)→刻薄的
(例)His tendency to utter acrimonious remarks alienated his audience.
說話刻薄的習(xí)慣使他疏遠了聽眾。
acrobat n.雜技演員, 隨機應(yīng)變者
(記)acro高+ bat走 →高空行走(如阿迪江)→雜技演員
參考：acrophobia恐高癥acronym首字母縮寫詞
actuate vt. 促使
(記)act行為+uate→使有作為→促使 參考：activate 刺激，使活潑
acuity n. 銳利，視力或觀察力敏銳;敏捷(acuteness of vision or perception; keenness)
acumen n.敏銳，聰明(keenness and depth of perception)
(類)alacrity·prompt=acumen·shrewd 敏捷·快速=敏銳·干練(同義)
(反)acumen
◆ unable to discerning 敏銳
◆ 不能辨別的
(記)acu(尖)+men →敏銳 參考：acupuncture 針灸
(例)His business acumen helped him to succeed where others had failed.
他在商業(yè)上的敏銳幫他在其他人失敗的地方獲得成功。
acute adj. 敏銳的，銳角的;(醫(yī))急性的(having a sudden onset 發(fā)作, sharp rise, and short course)
(類)perspicacity·acute=caprice·whimsical 敏銳·敏銳的=反復(fù)無常·多變的(名形同義)
(反)acute
◆ mild 急性的
◆ 溫和的
(例)acute disease. 急性病
adage n. 諺語(a saying often in metaphorical form that embodies a common observation)
(同)saying, word, proverb, saw 諺語, byword 格言，諺語，笑柄
(記)ad+age(時代)聯(lián)想：諺語在不同時代都禁得起檢驗。易混淆：badge徽章
adamant adj. 堅硬的;固執(zhí)的，不動搖的(unshakable especially in opposite)
(類)adamant·flexibility=refractory·control 堅固不柔軟=難以操作的不可控制
impossible·execute=adamant·move 不可能的不可操作=頑固的不改變路線
(反)vacillatory 動搖 incline to yield 容易妥協(xié)的
(記)a+dam大壩+ant 一個大壩上的螞蟻;如果不夠固執(zhí)和堅強，千里之堤，如何毀于蟻穴呢?
(例)He was adamant in his determination to punish the corrupt officials.
他下了決心，堅決懲治那些貪官污吏。
adapt vt. 修改，使適應(yīng)(to bring into correspondence or make suitable)
(反)adapt 修改
◆ remain unchanged 保持不變的
(例)a species that has adapted well to winter climes. 很適應(yīng)冬天氣候的物種
(記)ad+apt(靈巧的，適當(dāng)?shù)?本身就是一個詞啊)
addendum n. 附錄，補遺(a supplement to a book)
(類)addendum·document=postscript·letter 附錄附屬于文件=附言附屬于信件
(記)由add 而來，參考另外一詞：append 附加，添加
addict v. 沉溺，上癮(to devote(oneself)to something habitually)
(類)disabuse·error=rehabilitate·addiction
打消錯誤念頭·錯誤=回到從前狀態(tài)·上癮(動作與其相關(guān)對象)
inured·tolerance=addicted·dependency 習(xí)慣的容易忍受=上癮的容易依賴
(記)ad+dict(要求)→不斷要求→上癮 參考：dictator獨裁者
addition n. 加;增加物
(例)Our baby brother is an addition to our family. 新出生的弟弟使我們家多了一口人。
(記)in addition (also;as well as也;另外，加之)
in addition to(over and above; besides 加于…之上;除…之外又)
additive：adj. 附加的n.添加劑