单项选择题
A.100mm B.150mm C.200mm D.250mm
A.不应小于1.2mm,不应小于2.0mm B.不应小于1.5mm,不应小于2.0mm C.不宜小于1.2mm,不宜小于2.0mm D.不宜小于1.5mm,不宜小于2.0mm
A.不应小于4mm B.不应小于3mm C.不宜小于4mm D.不宜小于3mm