Her house _____ at 6 o’clock this morning and it _____ for about an hour.[ ]

A. was on fire; caught fire              

B. caught fire; was on fire

C. had caught fire; had been on fire    

D. caught a fire; was on fire

患者，男，72岁，下颌无牙颌，上颌仅余双侧尖牙，双侧尖牙牙体无缺损，向对颌伸长，并向近中倾斜，牙槽嵴吸收至约牙根2/3处，Ⅰ度松动，牙龈红肿，牙周袋深3mm。余无异常。

如两尖牙行RCT后，截冠，设计为磁性附着体固位总义齿修复，在余留牙处，义齿基托的伸展以下哪项合理（）.

A.余留牙唇侧骨组织倒凹大，义齿基托不覆盖基牙唇侧

B.为保证边缘封闭，义齿基托应在骨组织倒凹处充分缓冲，并伸展至黏膜转折处

C.建议患者外科手术修整基牙唇侧骨组织倒凹，义齿基托伸展至黏膜转折处

D.如患者接受，则义齿基托尽量覆盖基牙唇侧，保证义齿边缘封闭；如患者不接受，则义齿基托不覆盖基牙唇侧，并向患者说明对修复效果的影响

E.以上均不对