| | | | | | | ﹇ | | 20% ~ 40% | ︵2.8 ~ 3.5︶ 1 ︵ | ︶ | | | | | | | ︵ | ︶ | | | | | | | | | | ︔ | | | | | | | | | | 1. | | | | 2 | 2 . | | | | | | | | | | | 3. | PVC | | 1P 1.5P 2P ︵IP ≈ 735 ︶ | | | | 4. | | | | | ︔ | | | | | 5. | | | | | | |