通常直流Ⅰ、Ⅱ段母线电压应保持在（）V，其波动应（）。
参考答案：210～230；≤5％
请列式计算．
①82个0.125的和减去0.26除0.78的商，差是多少？
②6.75比一个数的5倍多2.75，求这个数．
These old women are fond of bargains, that's why they were so easily ________.[ ]
A. taken in
B. taken up
C. taken on
D. taken off
were so easily ________.[ ]