氨气（NH₃）燃烧反应的化学方程式为4NH₃ + 3O₂  ^点燃 6H₂O + 2N₂。该反应属于

A．置换反应

B．化合反应

C．分解反应

D．复分解反应

A shepherd’s crook is used to（）.

A.lower spring buoys into the water

B.find an anchor after the buoy has been lost

C.transfer a pennant wire to the anchor handling boat

D.clean chain as it is hauled into the rig