A.0s,3s B.0s,6s C.3s,6, D.6s,0s
A.點(diǎn)火成功 B.在高火燃燒時(shí) C.在低火燃燒時(shí) D.鍋爐小途熄火時(shí)
A.70s B.89s C.93s D.120s