檐口第一根挂瓦条应较高出一片瓦的厚度，并使第一排瓦紧贴檐口。
参考答案：错
If you happen to see the process of cooking in a restaurant, you might see the cook using rubbish oil, which is a common _____ in China nowadays.
A．sense
B．rule
C．practice
D．activity
电机绕组是进行( )转换的关键部件。
A．电流
B．电压
C．电机能量
D．电磁
