下列材料不属于永久性栓塞剂的是()
A.不锈钢圈
B.NBCA
C.PVA颗粒
D.明胶海绵颗粒
E.海藻酸钠微球
参考答案:D
解析:明胶海绵颗粒属于中效栓塞剂。
When producers expend resources to establish monopoly power in a market, this is called:()
A. surplus allocation.
B. resource rationalization.
C. rent seeking.
离心泵在运行中,泵的振动一般不应超过()mm
A.0.07
B.0.08
C.0.09
D.0.10