A.1 B.3 C.5 D.10
A.始端信號(hào)按鈕 B.以上都是 C.終端信號(hào)按鈕 D.延續(xù)終端按鈕
A.3‰長(zhǎng)大下坡道 B.6‰長(zhǎng)大下坡道 C.9‰長(zhǎng)大下坡道 D.10‰長(zhǎng)大下坡道