水流显著的海区，应每隔（）小时推算一个船位。
A.0.5
B.1
C.2
D.3
参考答案：B
–I didn’t know ______
-Neither did I.
A．what was happened to him
B．what the matter was with him
C．what was wrong with him
D．where was the History Museum
A．当单刀双掷开关与a连接时，电压表的示数为22V
B．当单刀双掷开关与b连接时，电压表的示数为11V
C．当单刀双掷开关与a连接，滑动变阻器触头P向上移动的过程中，电压表的示数不变，电流表的示数变大
D．单刀掷开关由a扳向b时（滑动变阻器触头P不动），电压表和电流表的示数均变大
sin
V