所谓辅助操舵装置是指在（）为驾驶船舶所必需的设备。
A.进出港时
B.避让等应急情况时
C.过狭水道时
D.主操舵装置失效时
参考答案：D
.
The last time we had great fun together was _________we were flying kites in Xinghai Square, which will be remembered forever.
A．when
B．in which
C．what
D．which
某双代号网络计划如下图所示。
则C工作的自由时差为（）。
A．0
B．1
C．2
D．3
