采用减压方式进行分馏操作，主要目的是为了防止较重组分在高温下分解而影响产品质量和收率
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Which three statements about the DHCP snooping feature on Cisco Nexus switches are true？ （）
A. DHCP snooping commands are not available until the feature is enabled with the feature dhcp- snooping command.
B. When you enable the DHCP snooping feature， the switch begins building and maintaining the DHCP snooping binding database.
C. The switch will not validate DHCP messages received or use the DHCP snooping binding database to validate subsequent requests from untrusted hosts until DHCP snooping is enabled globally and for each specific VLA
D. Globally disabling DHCP snooping removes all DHCP snooping configuration on the switch.
E. Globally disabling DHCP snooping does not remove any DHCP snooping configuration or the configuration of other features that are dependent upon the DHCP snooping feature.
研究者给家兔注射链脲佐菌素（可破坏胰岛细胞）后，会发现家兔血液中哪种激素含量降低（）
A. 生长激素
B. 肾上腺素
C. 胰岛素
D. 甲状腺激素
当河口拦门砂受沿岸输沙影响，导堤需兼顾拦截沿岸输砂功能时，单侧导堤应布置在沿岸（）。
A. 来砂方向一侧
B. 来砂方向对侧
C. 涨落潮深槽一侧
D. 浅滩一侧
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