65. at intervals 不时,每隔...
66. at large 大多数,未被捕获的
67. at last 终于
68. at least 至少
69. at length 最终,终于
70. at most 至多,不超过
71. at no time 从不,决不
72. at one time 曾经,一度;同时
73. at present 目前,现在
74. at someone's disposal 任...处理
75. at the cost of 以...为代价
76. at the mercy of 任凭...摆布
77. at the moment 此刻,目前
78. at this rate 照此速度
79. at times 有时,间或
80. aware of意识到
81. back and forth 来回地,反复地
82. back of 在...后面
83. back up后备,支援
84. bare of几乎没有,缺乏
85. be able to do能够
86. be around差不多