龈下刮治放人器械时,工作端平面与牙根面之间成的角度是
A.80°
B.60°
C.90°
D.40°
E.0°
参考答案:E
— Will the match be cancelled because of the bad weather?
— No. Rain or shine, the match will be held as _____.[ ]
A. schedule
B. scheduling
C. scheduled
D. to schedule
简述交通工程学的研究内容。