A.10~20s B.20~30s C.30~40s D.40~50s
A.塑料 B.橡膠 C.熱塑性橡膠 D.合成橡膠
A.混膠、切膠、塑煉 B.切膠、混膠、塑煉 C.塑煉、切膠、混膠 D.塑煉、混膠、切膠