A.8mm B.10mm C.12mm D.16mm
A.月牙形反射信號(hào) B.月牙形弱反射信號(hào) C.連續(xù)的小雙曲線形弱反射信號(hào) D.連續(xù)的小雙曲線形強(qiáng)反射信號(hào)