A. may B. must C. should D. can
A. digit B. figure C. diagram D. quantity
A. high-lying B. low-lying C. overpopulated D. overcrowded
A. with B. for C. among D. between
A. 先进性 B. 适用性 C. 成熟性 D. 可靠性 E. 经济合理性
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