A.3 B.4 C.5 D.6
A.10;50 B.15;50 C.10;75 D.15;75
A.2 B.3 C.5 D.10
A.滿掛安全網(wǎng) B.滿掛防護(hù)欄桿 C.掛安全繩 D.掛安全帶
A.10% B.15% C.20% D.25%