单选题 In honor of its second anniversary, Neticroix Gym gave its members______gift certificates for a two-hour group training session with one of its fitness specialists.
【正确答案】 D
【答案解析】解析：根据上下文语义，此处表示“为庆祝两周年而为会员提供免费商品券”，形容词(D)complimentary(赠送的)为正确答案。(A)durable意为“耐用的，持久的”，(B)probable意为“有可能的”，(C)elapsed意为“经过的，过去的”。