1.accretion n.增长( the process of growth or enlargement by a gradual build-up)；增加物( added matter or thing formed by the addition of such matter)
词根记忆：ac+cret(增加)+ion一增长
例:accretion disks吸积盘//This continuous process of accretion and succession would be interrupted only by hurricanes or storm flushings.
2.accrue v.自然增长，自然产生( to come about as a natural growth,increase, or advantage)
词根记忆：ac+crue(增加)--自然增长，自然产生
例:The benefits would accrue to the individual, while the costs would be spread among all users.
派生词:accrual(n.获利：自然增长)
3.accumulate v.积累( to gather or pile up)；堆积(to amass)
词根记忆：ac（不断）+cumul（堆积）+ate(使)一使不断堆积起来一积累
例:Recyclable trash that is allowed to accumulate for two weeks will attract rodents(啮齿动物)．
派生词:accumulation(n.集聚;积累)
4.accuracy n.准确（性），精确（性）( exactness)
词根记忆：ac(加强)+cur(注意)+acy(表性质)一十分注意一准确
例:The accrnacy of animals memories is difficult to determine through direct experimentation.
派生词:inaccuracy(n.误差，错误)
5.accurate a.正确的( correct)：精确的(exact)
例:Sailors needed highly accurate timepieces in order to compute their longitude.
派生词:inaccurate(a.不准确的)；accurately(ad.正确地：精确地)
6.accustomed a.(to)习惯的，适应的(adapted to existing conditions)
词根记忆：ac+custom(习惯，习俗)+ed 一习惯的
例:The recent immigrants have not yet become accustomed to American food.
7.acidity n.酸度，酸性( the quality, state, or degree of being acid)
词根记忆：acid(酸)+ity（名词后缀）一酸度
例:The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality.
8.acknowledge v.承认( to recognize as genuine or valid)；致谢(to express gratitude)
词根记忆:ac+knowledge(知道)一人人都知道，不得不承认一承认
例:Womens oral histories acknovdedge the influence of well-known women.
派生词:acknowledgement(n.承认；感谢)
9.acoustic a.听觉的，有关声音的( having to do with hearing or sound)
例:The use of acoustic alarms increases the number of commercial fish caught by the fishing companys boats.
派生词:acoustics(n.声学)
10.acoustical a.声学的，听觉的(of or relating to the sense or organs of hearing, to sound, or to the science of sounds)
词根记忆:来自acoustic(a.声学的；音响的)
例:The male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals.
派生词:acoustically( ad.听觉上;声学上)