Sequential circuit is a common logic device whose output values, at a given instant, depend upon its input values and the internal state at that instant, and whose internal state depends upon the (66) preceding input values and the preceding internal state. A sequential circuit can assume a finite number of internal states and may therefore be regarded, from an abstract (67) , as a finite (68) .

Combinational circuit is another logic device whose output values, at any given instant, depend upon the input values at that instant. A combinational circuit is a (69) of a sequential circuit whose internal state is not taken (70) .

（68）处填（）。

A．automaton

B．robot

C．manipulator

D．man-machine system

振动沉桩法的特点是( )。

A．机具设备复杂

B．效能高

C．适用范围宽

D．适用于黏性土