A.20mm B.20~25mm C.20~30mm D.30mm
A.上蓋板進(jìn)風(fēng) B.橡膠堆下進(jìn)風(fēng) C.上下同時(shí)進(jìn)風(fēng) D.附加空氣室進(jìn)風(fēng)
A.10mm B.30mm C.20mm D.40mm