下面哪个不是牙髓感染的特发性因素
A．病毒感染B．放射性骨坏死C．颌骨囊肿D．颌骨肿瘤E．备洞产热造成的温度刺激
参考答案：E
—Dad, when shall we go to visit my grandpa?
—Grandpa is very busy at present．We'll go to see him whenever __________.
A．he is convenient
B．he will be convenient
C．it is convenient to him
D．it will be convenient to him
癌抗原125（CA125）
