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v. 即兴演唱，临时穿插，信口说出

actual, actuality, actually, actuarial, actuary, actuate, acuity, acumen, acupuncture, acupuncturist, acute, acute angle, acute mark, acutely, acuteness, AD, ad hoc, ad infinitum, ad lib, ad nauseam, adage, adagio, Adam, Adam's apple, adamant, adamantly, adapt, adapt oneself to, adapt to, adapt...to, adaptability, adaptable, adaptation, adaption, adaptive, adaptor, ADC, add, add sth. to sth., add up,