与眼有关的脑神经有几对
A．2对
B．4对
C．6对
D．8对
参考答案：C
You mustn't _____ until he comes back.[ ]
A. be away
B. leave
C. be left
D. have been
与牙周病发生关系最密切的是
A．龈上菌斑B．龈下菌斑C．龈下非附着菌斑D．龈下附着菌斑E．软垢
