每日雅思词汇：高频动词　　激发，鼓励encourage = motivate = stimulate = spur 　　认为think = assert = hold = claim = argue 　　完成complete = fulfill = accomplish= achieve 　　保留keep = preserve = retain = hold 　　有害于destroy = impair = undermine = jeopardize 　　减轻 ease = alleviate = relieve = lighten