吸烟对青少年的影响错误的是（）
A.影响大脑功能
B.促进性发育
C.影响呼吸系统发育
D.易产生毒品依赖性
参考答案：B
It is said that the early European playing-cards ______ for entertainment and education.[ ]
A. were designed
B. have designed
C. have been designed
D. were being designed
嵌塞的主要原因有
A．牙龈肿胀B．严重的牙周病C．骨下袋的形成D．接触点消失或改变E．牙齿松动
