认为长期债券是短期债券的理想替代物是( )。

A．市场预期理论
B．流动性偏好理论
C．市场分割理论
D．优先偏好理论

The development of（）led to the fully automatic ARPA systems installed on commercial ships.

A.SeaTalk

B.powerful microprocessors and mega memory capacity

C.chartplotter

D.small-scale chart