“上下课的铃声是音乐，水龙头分为高中低，课桌椅可以调节高矮。”这些措施体现了《中华人民共和国未成年人保护法》关于________的规定。 [ ]

A．学校保护

B．家庭保护

C．社会保护

D．司法保护

All of the guests ________ by 9 o'clock, but the host ________ until 15 minutes later.[ ]

A. arrived; didn't show up    

B. had arrived; didn't show up

C. arrived; hadn't turned up    

D. had arrived; hadn't turned up