灰渣泵与其轴封泵之间设有连锁，以防误操作。
参考答案：对
In 1911, Madame Curie received a second Nobel Prize for her research, the first person
in the world _____ two Nobel Prizes. [ ]
A. receiving
B. received
C. to receive
D. being received
下面（）数据库模型被认为是最通用的。
A．层次模型
B．树状模型
C．网络模型
D．关系模型
