替牙期儿童颌面部感染的多见原因是
A．外伤性
B．腺源性
C．耳源性
D．血源性
E．牙源性
参考答案：B
复发和难治性霍奇金病影响化疗的不良预后因素包括（）。
A.B症状
B.结外侵犯
C.老年患者
D.原发耐药
E.以上都正确
— Can you come to my birthday party?
— _____. [ ]
A. No, I won't go
B. Sorry, I can't. I have to study for a test
C. I can't go there
D. I have no time
