别人跟你寒暄, 问你“How are you today?", 你觉得还不错, 你可以回答:_____.
A. I am busy, thank you.
B. I am fine, thank you.
C. I am cold, thank you.
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你父亲的朋友买了一辆新车,你想知道它是什么牌子的, 你可以问:___。
A. What make is it?
B. How is it?
C. Is this your German car?
你想知道你的新同学汤姆来自哪个国家,你可以问他:______.
A. How are you today?
B. What's your job?
C. What nationality are you?
如图所示,用泵将贮槽中密度为1000kg/m3的碱液送到蒸发器内,蒸发器上部的蒸发室内操作压强为26670Pa(真空度),蒸发器进料口高于贮槽内液面7m,贮槽内液面维持恒定,其上方压强为大气压,管路内流量为20m3/h,碱液流经全部管路的能量损失为140J/kg,求泵的有效功率。管路的内径为60mm。