下列肿瘤中属恶性肿瘤的是（）。 A.精原细胞瘤 B.脂肪瘤 C.乳腺腺瘤 D.甲状腺

由三条线段围成的图形叫______，它有______个内角，它的内角和是______．

花斑癣又名（）

A．白秃疮 

B．肥疮 

C．疠风 

D．鹅掌风 

E．紫白癜风

除竞争性工资差别之外的另外一种非补偿性工资差别，这是（）。

A.补偿性工资差别

B.竞争性工资差别

C.垄断性工资差别

D.季节性工资差别

用适当的介词填空。

1. The writer was educated _____ a very good school.

2. He received a title _____ a reward for his service to the na- tion.

3. She rewarded the boy with＄10_____ his help.

4. They stopped me _____ going out of the door.

5. The teacher refused to have his daughter in his class, for fear _____ showing favor to her.

造成110kV少油断路器泄漏电流超标的主要原因是什么？