苯蒸馏开车时，须先启动（）。
A、苯贮槽底层液泵
B、萃取塔苯进料泵
C、苯泵槽粗苯出料泵
D、苯泵槽精苯出料泵
参考答案：B
After the trainer was sure that the whale could look after itself, he __________it into the sea.
A．transported
B．unloaded
C．released
D．handled
由社会生产方式决定的属性就是领导的（）属性。
A.科学
B.社会
C.自然
D.阶级
