隧道通风系统主要设备包括（）
A.TVF风机
B.空调柜
C.组合式电动风阀
D.消声器
参考答案：A, C, D
产品进入成熟期，竞争日益激烈时，应采用（）。
A.无差异市场营销
B.差异市场营销
C.密集（集中）市场营销
D.统一市场营销
－ What a great success the exhibition was last night !
－_______ , especially it ______ those who have a preference for the beauty of nature .
A．So it did ; appeals to
B．So did it , interested
C．So was it ; attracted
D．So it was ; appealed to
