GK阀风筒盖边缘允许有1处不超过40mm的缺损更换。
参考答案:错
My father and my mother have been married for 30 years, and never once ____ with each other.[ ]
A. have they quarreled
B. they have quarreled
C. did they quarrel
D. had they quarreled
简述课堂问题行为的只要影响因素。