变压器的铁芯一般都用（）方法，其目的是使（）坚固和减少漏磁。
参考答案：交错叠装；铁芯结构
根据句意或首字母填入所缺单词。
1. Don't worry! They arc living in s______.
2. A _______ some students, buses are not popular.
3. This teacher is very popular a _______ the students.
4. What's y _______ favorite transportation?
5. Not many people can a _______ to buy a car.
国标规定，二硫腙比色法测锌时，防止铜、汞、铅、铋与镉离子干扰的试剂为（）
A.硫代硫酸钠溶液，用乙酸调至pH4.5～5.5
B.碘化钾溶液
C.氯化钠溶液
D.氯化亚锡溶液
E.亚硫酸钠溶液
