变压器铁心的材料是（）
A.硬磁性材料
B.软磁性材料
C.矩磁性材料
D.逆磁性材料
参考答案：B
选词填空
1. People eat dinner_________ (in/on) the evening.
2. Do you want to know_________(about/around) my morning?
3. Please tell_________(I/me) about your classmates.
4. Thanks_________(of/for) your help.
5. Does he_________(have/has) a shower every day?
6. What time does he get_________ (to/for) school.
世界各国对城市开发建设的控制分为哪两种类型？我国又属于哪种类型？
