电能表和互感器应办理（）方可报废，报废后不得私自处理或变卖。
A.返库手续
B.审批手续
C.上报手续
D.注销手续
参考答案：B
若x：y：z=2：7：5，且x-2y+3z=6，则x=______，y=______，z=______．
When you are ______, you can come to me for help. [ ]
A. in trouble
B. trouble
C. in dangerous
D. in matter
