---Excuse me, I want to buy some books, but I can’t find a book shop.

--- I know _______ nearby. Come on. I’ll show you.

A．it

B．some

C．one

D．that

瓦斯保护的主要优点是能反映变压器油箱内的各种故障，灵敏性高、结构简单、动作迅速。它和电流速断、电流差动保护等都是变压器的快速保护，属于主要保护。