10KV高压隔离开关合闸时，三相动闸刀与静触头同时接触，各相前后相差（）才算合格。
A.2mm
B.2.5mm
C.3mm
D.4mm
参考答案：D
下列计算中，正确的是（ ）
A．（-x6）÷（-2x2）=3x3
B．a+a=a2
C．（a3）2=a6
D．x3•x4=x12
.
Who is the person ____is talking about the accident ___happened on Highway 104?
A．which, which
B．who, what
C．that, that
D．what, what
